feat(secret scanning): Support pull_request_comment_url

[chrisallenlane]

Modify SecretScanningAlertLocationDetails to recognize API responses of type pull_request_comment_url.

Per the documentation available here:
https://docs.github.com/en/rest/secret-scanning/secret-scanning?apiVersion=2022-11-28

For requests to this route:

curl -L \
  -H "Accept: application/vnd.github+json" \
  -H "Authorization: Bearer <YOUR-TOKEN>" \
  -H "X-GitHub-Api-Version: 2022-11-28" \
  https://api.github.com/repos/OWNER/REPO/secret-scanning/alerts/ALERT_NUMBER/locations

The API may return JSON that matches the following shape:

// ...
  {
  "type": "pull_request_comment",
  "details": {
    "pull_request_comment_url": "https://api.github.com/repos/octocat/Hello-World/issues/comments/1825855898"
  }
},
// ...

(I'm sorry I can't provide a more specific link. The docs don't make one available.)

Previously, go-github would not expose that data to the user. This change makes it available by adding a new field (PullRequestCommentURL) to the SecretScanningAlertLocationDetails struct.

Tests are included.

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[chrisallenlane]

If someone is able to re-run the cla/google check, I have signed the CLA. Thanks.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.30%. Comparing base (2b8c7fa) to head (4a031cd).
Report is 166 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3344      +/-   ##
==========================================
- Coverage   97.72%   92.30%   -5.42%     
==========================================
  Files         153      176      +23     
  Lines       13390    15031    +1641     
==========================================
+ Hits        13085    13874     +789     
- Misses        215     1064     +849     
- Partials       90       93       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[gmlewis]

Thank you, @chrisallenlane !
LGTM.
Merging.