support optional ul_name in profiles

[dmitryperets]

Allow an additional (explicit) option to deal with tunnel naming conflicts and at the same time allow adding the local side identifier to the name.

Whenever ul_name is configured for an interface in the device profile, its value will be used in the naming of all the tunnels built from this interface. So that the naming convention becomes:

<ul_name>-H<hub_index>_<ol_type>

This is optional. If ul_name is not set, the naming convention remains as before. The automatic indexing mechanism to deal with duplicates remains in place.

02-Edge-Overlay.j2 change:

{% set ul_name = i.ul_name~"-" if i.ul_name is defined else "" %}
{% set ol_tun = ul_name~"H"~hubloop.index~"_"~i.ol_type %}