fix: return 200 status codes on rejection to ensure error message renders in git client

[kriswest]

resolves #1177
PR #1164 changed the status codes returned on rejected pushes to better represent the outcome (forbidden 403, invalid request 401, server error 500) however git clients don't render the message returned for these status codes. Hence, this PR switches all response back to the 200 status code, which will, render the message. It also adds a comment on each rejection to inform future maintainers why that code is returned.

When a 403 is returned on reject:

% git push
Enumerating objects: 5, done.
Counting objects: 100% (5/5), done.
Delta compression using up to 14 threads
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 309 bytes | 309.00 KiB/s, done.
Total 3 (delta 2), reused 0 (delta 0), pack-reused 0
error: RPC failed; HTTP 403 curl 22 The requested URL returned error: 403
send-pack: unexpected disconnect while reading sideband packet
fatal: the remote end hung up unexpectedly
Everything up-to-date

When a 200 is returned on reject:

% git push
Enumerating objects: 5, done.
Counting objects: 100% (5/5), done.
Delta compression using up to 14 threads
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 309 bytes | 309.00 KiB/s, done.
Total 3 (delta 2), reused 0 (delta 0), pack-reused 0
remote: 	Your push has been blocked (kristopher.west@natwest.com is not allowed to push on repo https://github.com/*****.git)
fatal: the remote end hung up unexpectedly
fatal: the remote end hung up unexpectedly
error: failed to push some refs to 'http://localhost:8000/github.com/*****.git'

[netlify]

✅ Deploy Preview for endearing-brigadeiros-63f9d0 canceled.

Name	Link
🔨 Latest commit	7210153
🔍 Latest deploy log	https://app.netlify.com/projects/endearing-brigadeiros-63f9d0/deploys/68b1ba6d7511050009a2a2b6

[kriswest]

@jescalada one more to get in - I was testing the response directly and not whether they render through a git client nicely, which they did not.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 82.76%. Comparing base (00c11bd) to head (7210153).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/proxy/routes/index.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1178   +/-   ##
=======================================
  Coverage   82.76%   82.76%           
=======================================
  Files          66       66           
  Lines        2780     2780           
  Branches      332      332           
=======================================
  Hits         2301     2301           
  Misses        431      431           
  Partials       48       48           

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[jescalada]

LGTM! I noticed this issue as well, thanks for diagnosing and fixing it so quickly! 🚀