✨ githubrepo: Allow providing an already authenticated transport

[jeffmendoza]

Way back in 2.0 the constructor took a github.Client directly, which is what Allstar instantiated to then run scorecard checks. With the current code, there is no way to override the built-in roundtripper.NewTransport which uses its own methods to authenticate.

To allow Allstar to use the current code, we need to create this client and provide a pre-authenticated transport (or http client, or github client).

cc @justaugustus

[justaugustus]

@jeffmendoza -- Hehe, I just opened a branch for this! Mind if I push a few things on top of this PR?

[github-actions]

Integration tests success for
[0d49b00]
(https://github.com/ossf/scorecard/actions/runs/1850042265)

[codecov-commenter]

Codecov Report

Merging #1644 (0d49b00) into main (cda7a1b) will increase coverage by 2.83%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #1644      +/-   ##
==========================================
+ Coverage   56.12%   58.95%   +2.83%     
==========================================
  Files          72       72              
  Lines        6493     6495       +2     
==========================================
+ Hits         3644     3829     +185     
+ Misses       2604     2415     -189     
- Partials      245      251       +6     

[azeemshaikh38]

Will we need to make a Scorecard release for AllStar to be able to consume it? If so, please do chime in #1621. We can wait for this PR to go in before cutting the release.

[justaugustus]

@jeffmendoza -- Hehe, I just opened a branch for this! Mind if I push a few things on top of this PR?

Will we need to make a Scorecard release for AllStar to be able to consume it? If so, please do chime in #1621. We can wait for this PR to go in before cutting the release.

Merged. Will push any updates as a follow-up! Thanks Jeff!