Feature: Add PublishValue and Subscribe from kuksa.val.v2

[lukasmittag]

This modifies as well the generation of the files from submodules. Needs to be checked if this works as well for the pypi package or if we need to change back.

[erikbosch]

Replace submodule URL. If CI pass ok to merge

[erikbosch]

Not related to this PR, but I am thinking if we should add

proto/**/*.py

to the .gitignore of kuksa-databroker so that the submodule isn't reported as dirty after this command

[erikbosch]

Tested it locally, if you change the two infoto debug I am happy

(alternatively keep them as info but add a TODO comment that they longterm shall be debug)

[erikbosch]

LGTM