Hide obsolete Job summaries (#902)

- Injects a `<!-- gradle-job-summary: ${jobCorrelator} -->` marker on
each job summary
- Lists 100 last comments: unfortunately there is no API to specifically
filter for comments, and checking the last 100 comments (the limit) is
usually enough and does not require iterating over pages
- Mutate comments having this expected marker

I tried to add some tests, but I'm not familiar enough to setup a
complete test suite with proper mocking of GitHub/Octokit with jest.

I could potentially extract the `prComment` creation to check for the
marker presence, let me know.

Note: it seems like there is currently an issue on mutating comments as
`OUTDATED` through graphql. Although it does not work as expected
(flagging as OUTDATED) the comments are still minimized, which is what
we want.
- https://github.com/orgs/community/discussions/19865

Implements #176

---------

Co-authored-by: Daz DeBoer <daz@gradle.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/setup-gradle.md

@@ -548,6 +548,11 @@ jobs:
     - run: ./gradlew build --scan
 ```
 
+When a comment is added, any earlier Job Summary comments posted by the same job on that Pull Request are
+automatically minimized, so only the most recent result remains expanded. This also applies when
+`add-job-summary-as-pr-comment: 'on-failure'` is used: once a later run of the job succeeds, the previous
+failure comment is collapsed.
+
 Note that to add a Pull Request comment, the workflow must be configured with the `pull-requests: write` permission.