Add support for unix domain sockets

[argerus]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 17.17172% with 82 lines in your changes missing coverage. Please review.

Project coverage is 59.35%. Comparing base (9359eff) to head (6ecc025).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
databroker/src/main.rs	0.00%	58 Missing ⚠️
databroker/src/grpc/server.rs	41.46%	24 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #94      +/-   ##
==========================================
- Coverage   59.65%   59.35%   -0.30%     
==========================================
  Files          33       33              
  Lines       15964    16048      +84     
==========================================
+ Hits         9523     9525       +2     
- Misses       6441     6523      +82     

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[erikbosch]

I think we should add some documentation. Some things I think could be useful to include/mention:

• Does the CLI support it?
• Provide a example where we use the new argument. Preferably also with a client (if supported)
• Mention that the socket is not protected by TLS or similar, that you may need to consider to mechanisms like MAC/DAC for protecting the socket
• Mention that token functionality works the same way as for TCP/IP connection.

When merged we should preferably also mention something on how to test it in https://github.com/eclipse-kuksa/kuksa-databroker/wiki/Release-Testing - I think we at least shall have some form of smoke test, manual or in Github CI to verify that it works before releasing.

[erikbosch]

Do we want to get rid of uds everywhere, i.e. rename this one to serve_unix_domain_socket or similar?

[erikbosch]

Rebased the PR and added some basic documentation. Also addressed two of the comments

[erikbosch]

LGTM