[Tooling] Run Danger on the Linter Agent

[iangmaia]

This PR uses the new Linter Agent on Buildkite to run the Danger and SwiftLint jobs.

Because Danger will now run on Buildkite, this PR uses a new GitHub Actions workflow (see https://github.com/Automattic/dangermattic/pull/64 for more details) to retry the Buildkite jobs when the PR state (such as the milestone and labels) changes.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20807-568ab66
	Commit	568ab66584d74781f76a9d388a15dfdc2266d8fa
	Direct Download	jetpack-prototype-build-pr20807-568ab66.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20807-568ab66
	Commit	568ab66584d74781f76a9d388a15dfdc2266d8fa
	Direct Download	wordpress-prototype-build-pr20807-568ab66.apk

Note: Google Login is not supported on these builds.

[mokagio]

Toggling the "tooling" label to see the GitHub Action - Buildkite - GitHub comment integration at play.