serial interface: add command parser for protocol

[dhebbeker]

Purpose

Create a command parser which is capable to interpret the commands from serial interface according to the defined protocol.

Resolves #60

Acceptance criteria

• [x] It is OK for this version to respond with dummy responses (format does not need to follow protocol)
• [x] All arguments of the commands shall be understood (test by echo the values to serial interface)
• [x] Dummy functions for the commands shall be called (test by echo a string on serial interface)

Todos

• [x] remove trim functionality as it is not used
• [x] add member function to Command which generates a string which is intended to specify the correct use of the command (command line format)
• [x] handle the case that the command line can not be correctly interpreted outside of Command by printing a message
• [x] refactoring: check which function shall be member functions
• [x] add documentation
• [x] test: add appropriate test cases (check for code coverage)
• [x] create dedicated namespace
• [x] add test case for string helper functions
• [x] add documentation for string helper functions
• [x] add documentation on how to use the command line interpreter

Changes

• .github/workflows/platformio.yml: Added test execution to workflow.
• lib/3rd_party_adapters/serial_port.cpp: Change line extraction to omit line ending characters and empty lines.
• lib/application_business_rules/Protocol.*: This implements the protocol (here: dummies) by using the command line interpreter.
• lib/application_business_rules/command_line_interpreter.hpp: Essentially provides Option and Command class templates which can be used to call a function with some arguments based on a command line.
• lib/enterprise_business_rules/string_helpers.*: Add helper functions which can be used to operate on strings.
• platformio.ini: Add configuration for unit tests.
• src/main.cpp: Attach ProtocolHandler to serial port.
• test/test_cli/test_cli.cpp: Unit test for command line interpreter.
• test/test_serial_port/test_serial_port.cpp: Adjust to changed fetching of lines. The end of line character is omitted now.
• test/test_string_helpers/test_string_helpers.cpp: Unit test for string helpers.

[dhebbeker]

Tested also with real device:

 begin program '/home/dhebbeker/pro/time-tracker/src/time-tracker.ino compiled at Nov 30 2023 21:50:08
---- Sent utf8 encoded message: "list\n" ----
this is a list: a, b, c, ...
---- Sent utf8 encoded message: "list\n" ----
this is a list: a, b, c, ...
---- Sent utf8 encoded message: "edit --name \"hello world\"\n" ----
Edit id(0) label('hello world') duration(0)
---- Sent utf8 encoded message: "edit --name \"@²³ß\\\"ä\" --duration 1337\n" ----
Edit id(0) label('@²³ß"ä') duration(1337)

:heavy_check_mark: