python: add abstraction for the RoR, and advertise a RoR

New features:

its-quadkeys: new abstraction of the quadkeys system
its-info: advertise a region of responsibility (RoR)

How to test:

Prerequisites:
- an MQTT broker running
- an mqtt client listening on the info topic, like: mosquitto_sub -h BROKER -p PORT -u USERNAME -P PASSWORD -t info

run the its-quadkey test-suite:

$ cd ${ITS_CLIENT_GIT}/python/its-quadkeys
$ ./quadkeys-test

install its-quadkeys and its-info:
```
$ cd ${ITS_CLIENT_GIT}/python/
$ pip3 wheel -w wheels ./its-quadkeys/ ./its-info/
$ pip3 install wheels/*.whl
```
Also take note of where the its-info script has been installed (e.g. ${HOME}/.local/bin); replicate that path in the following tests.
run its-info without a RoR:
- adapt the configuration file its-info.cfg to match your setup, esp. the MQTT settings and use a short period (e.g. 10s), but leave the RoR section empty
- run its-info:
```
$ ${HOME}/.local/bin/its-info --config its-info.cfg
```
- stop its-info (with Ctrl-C)
run its-info with a RoR:
- update the configuration file its-info.cfg with a RoR section:
```
[RoR]
type = static
path = /tmp/its-info-ror.json
reload = yes
```
- run its-info:
```
$ ${HOME}/.local/bin/its-info --config its-info.cfg
```
- wait for the next MQTT message
- create a RoR file in /tmp/its-info-ror.json; a RoR file is just a json list of strings, each string a quadkey:
```
[
  "03131",
  "03133",
  "1202"
]
```
- wait for the next MQTT message
- update a RoR file in /tmp/its-info-ror.json, add, remove, and/or modify the quadkeys:
```
[
  "1202",
  "1200",
  "12011"
]
```
- wait for the next MQTT message
- remove /tmp/its-info-ror.json
- wait for the next MQTT message
- stop its-info (with Ctrl-C)

Expected results:

the MQTT broker and MQTT clents are running

the test suite passes:

QuadKey in: OK
QuadKey not in: OK
QuadKey split (depth): OK
QuadKey split (extra_depth): OK
QuadKey neighbours: OK
QuadZone optimise: OK
QuadZone optimise (merge-reduce): OK
QuadZone serialise: OK
QuadZone neighbours (depth 7): OK
QuadZone neighbours (depth 6): OK
QuadZone addition (neighbours 7): OK
QuadZone addition (neighbours 6): OK
QuadZone intersection: OK
QuadZone substraction (neighbours 7): OK
QuadZone substraction (neighbours 6): OK
QuadZone substraction (quadkeys): OK
QuadZone symmetric substraction (xor): OK

the python modules are installed:

Processing ./its-quadkeys
  Preparing metadata (setup.py) ... done
Processing ./its-info
  Preparing metadata (setup.py) ... done
Collecting linuxfd==1.5
  Downloading linuxfd-1.5.tar.gz (14 kB)
  Preparing metadata (setup.py) ... done
Collecting netifaces==0.11.0
  Downloading netifaces-0.11.0.tar.gz (30 kB)
  Preparing metadata (setup.py) ... done
Collecting paho-mqtt==1.6.1
  Downloading paho-mqtt-1.6.1.tar.gz (99 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 99.4/99.4 KB 3.5 MB/s eta 0:00:00
  Preparing metadata (setup.py) ... done
Building wheels for collected packages: its-quadkeys, its-info, linuxfd, netifaces, paho-mqtt
  Building wheel for its-quadkeys (setup.py) ... done
  Created wheel for its-quadkeys: filename=its_quadkeys-0.0.0-py3-none-any.whl size=6332 sha256=6607bcb1acc265c64af10b2ee7fb670f4e98dbb673549012c32e4d5fb796d1a3
  Stored in directory: /home/foo/.cache/pip/wheels/33/82/1a/cee230c08b5b4815b3921b8b1c119bbf3ac23ed747ac8f0ca6
  Building wheel for its-info (setup.py) ... done
  Created wheel for its-info: filename=its_info-0.0.0-py3-none-any.whl size=4441 sha256=74422eb0cd9107892dcc959e2f0ed46633ff1e1b0008d0d996988645bcb68a3a
  Stored in directory: /home/foo/.cache/pip/wheels/a5/13/37/641ec846d142b5417b69bd9d9c42dbba19dc7c814e27c92a7e
  Building wheel for linuxfd (setup.py) ... done
  Created wheel for linuxfd: filename=linuxfd-1.5-cp310-cp310-linux_x86_64.whl size=54043 sha256=14676de4dbc79103c68084716f58657e0fd19a80e48a50334d0071c15ac4bc6c
  Stored in directory: /home/foo/.cache/pip/wheels/47/a9/1c/0d9819f7f8440c2017d5b8d96f52cc49f519d2b302a2a769fd
  Building wheel for netifaces (setup.py) ... done
  Created wheel for netifaces: filename=netifaces-0.11.0-cp310-cp310-linux_x86_64.whl size=35018 sha256=e48db67f0d392dbd50f5469260030214972bb512fde46a6dbf2c8e87c963c6ee
  Stored in directory: /home/foo/.cache/pip/wheels/48/65/b3/4c4cc6038b81ff21cc9df69f2b6774f5f52e23d3c275ed15aa
  Building wheel for paho-mqtt (setup.py) ... done
  Created wheel for paho-mqtt: filename=paho_mqtt-1.6.1-py3-none-any.whl size=62133 sha256=8b342a920d6d61a7acf3630b1becc3668d91eaa43430047b31b697dbf9f07fca
  Stored in directory: /home/foo/.cache/pip/wheels/8b/bb/0c/79444d1dee20324d442856979b5b519b48828b0bd3d05df84a
Successfully built its-quadkeys its-info linuxfd netifaces paho-mqtt

Defaulting to user installation because normal site-packages is not writeable
Processing ./wheels/its_info-0.0.0-py3-none-any.whl
Processing ./wheels/its_quadkeys-0.0.0-py3-none-any.whl
Processing ./wheels/linuxfd-1.5-cp310-cp310-linux_x86_64.whl
Processing ./wheels/netifaces-0.11.0-cp310-cp310-linux_x86_64.whl
Processing ./wheels/paho_mqtt-1.6.1-py3-none-any.whl
Installing collected packages: paho-mqtt, netifaces, linuxfd, its-quadkeys, its-info
  WARNING: The script its-info is installed in '/home/foo/.local/bin' which is not on PATH.
  Consider adding this directory to PATH or, if you prefer to suppress this warning, use --no-warn-script-location.
Successfully installed its-info-0.0.0 its-quadkeys-0.0.0 linuxfd-1.5 netifaces-0.11.0 paho-mqtt-1.6.1

the MQTT client dumps the info messages, without a RoR, e.g.:

{
  "type": "broker",
  "version": "1.2.0",
  "instance_id": "ID",
  "instance_type": "local",
  "running": true,
  "timestamp": 1686809196359,
  "validity_duration": 20
}

the MQTT client dumps the info messages, with or without the RoR, depending on the presence and content of the RoR file:

first, messages without a RoR are reported

then messages with the first RoR (aka _servicearea):

{
  "type": "broker",
  "version": "1.2.0",
  "instance_id": "ID",
  "instance_type": "local",
  "running": true,
  "timestamp": 1686809196359,
  "validity_duration": 20,
  "service_area": {
    "type": "tiles",
    "quadkeys": [
      "03131",
      "03133",
      "1202"
    ]
  }
}

then messages with the first RoR:

{
  "type": "broker",
  "version": "1.2.0",
  "instance_id": "ID",
  "instance_type": "local",
  "running": true,
  "timestamp": 1686809196359,
  "validity_duration": 20,
  "service_area": {
    "type": "tiles",
    "quadkeys": [
      "1200",
      "12011",
      "1202"
    ]
  }
}

then messages without a RoR

Orange-OpenSource / its-client

python: add abstraction for the RoR, and advertise a RoR #83