feat: Implement missing push rules

[srgustafson8]

Adds support for the missing Push Rules - Restrict file path length, Restrict file extensions and Restrict file size with tests.

Closes#3274

[srgustafson8]

Tests output:

testing .
? github.com/google/go-github/v65/test/integration [no test files]
github.com/google/go-github/v65/test/fields coverage: 0.0% of statements
ok github.com/google/go-github/v65/github 8.592s coverage: 99.4% of statements
testing example
github.com/google/go-github/v65/example/codespaces/newusersecretwithxcrypto coverage: 0.0% of statements
github.com/google/go-github/v65/example/appengine coverage: 0.0% of statements
github.com/google/go-github/v65/example/basicauth coverage: 0.0% of statements
github.com/google/go-github/v65/example/codespaces/newreposecretwithxcrypto coverage: 0.0% of statements
github.com/google/go-github/v65/example/actionpermissions coverage: 0.0% of statements
github.com/google/go-github/v65/example/migrations coverage: 0.0% of statements
github.com/google/go-github/v65/example/commitpr coverage: 0.0% of statements
github.com/google/go-github/v65/example/listenvironments coverage: 0.0% of statements
github.com/google/go-github/v65/example/newfilewithappauth coverage: 0.0% of statements
github.com/google/go-github/v65/example/newrepo coverage: 0.0% of statements
github.com/google/go-github/v65/example/ratelimit coverage: 0.0% of statements
github.com/google/go-github/v65/example/newreposecretwithxcrypto coverage: 0.0% of statements
github.com/google/go-github/v65/example/simple coverage: 0.0% of statements
github.com/google/go-github/v65/example/tagprotection coverage: 0.0% of statements
github.com/google/go-github/v65/example/tokenauth coverage: 0.0% of statements
github.com/google/go-github/v65/example/topics coverage: 0.0% of statements
testing scrape
ok github.com/google/go-github/scrape (cached) coverage: 59.4% of statements
github.com/google/go-github/scrape/example/scrape coverage: 0.0% of statements
testing tools
ok tools/metadata (cached) coverage: 81.7% of statements```

[gmlewis]

Thank you, @srgustafson8 !
Just a few minor tweaks, please, then we should be ready for a second LGTM+Approval from any other contributor to this repo before merging.

If you have a moment, would you mind taking a look at some of the other outstanding PRs and give them code reviews, please? Of note is #3254 where the author is expressing desire to merge ASAP. Thank you!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.01%. Comparing base (2b8c7fa) to head (14dddd8).
Report is 128 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #3294 +/- ##
==========================================
- Coverage 97.72% 93.01% -4.72% 
==========================================
Files 153 171 +18 Lines 13390 11777 -1613 ==========================================
- Hits 13085 10954 -2131 - Misses 215 729 +514 - Partials 90 94 +4 

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[gmlewis]

Thank you, @srgustafson8 !
LGTM.

Awaiting second LGTM+Approval from any other contributor to this repo before merging.

[tomfeigin]

LGTM

[air-hand]

LGTM

[gmlewis]

Thank you, @tomfeigin and @air-hand !
Merging.