feat: add TLS support to API/UI service

[fabiovincenzi]

Fixes #1408
Add HTTPS on port 8444 (configurable via GIT_PROXY_HTTPS_UI_PORT) to the API/UI service, using the existing tls.enabled/key/cert config fields already used by the proxy. HTTP and HTTPS run in parallel.

[netlify]

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[codecov]

Codecov Report

❌ Patch coverage is 90.32258% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.28%. Comparing base (ad58c5a) to head (e02b146).

Files with missing lines	Patch %	Lines
src/service/index.ts	90.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1414      +/-   ##
==========================================
+ Coverage   90.21%   90.28%   +0.06%     
==========================================
  Files          69       69              
  Lines        5511     5558      +47     
  Branches      944      956      +12     
==========================================
+ Hits         4972     5018      +46     
  Misses        521      521              
- Partials       18       19       +1     

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[jescalada]

Code-wise LGTM, might want another look from @kriswest to make sure.

[kriswest]

@fabiovincenzi (note from meeting) it would be great to get this covered in the Config reference and getting started guide before its merged.

[jescalada]

LGTM! Should be good to ship in 2.1 👍🏼