Generate `GoogleAnalyticsAdminV1alphaAdSenseLink` for Google API Client Library

[tofumatt]

Feature Description

We need to replicate the Google API Client library's GoogleAnalyticsAdminV1alphaAdSenseLink for the REST Route we'll need to get linked accounts. See: https://docs.google.com/document/d/1-JenwPTAkw0eTkmESzjTOfgphs9qpRYH0h3xk_s3a4o/edit#heading=h.mjj6lw6stv0x

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Do not alter or remove anything below. The following sections will be managed by moderators only.

Acceptance criteria

• The properties.adSenseLinks.list AdSense API method should be callable from PHP code in a similar manner to the existing API methods.

Implementation Brief

• [x] Generate the Google_GoogleAnalyticsAdminV1alphaAdSenseLink class, and any related dependencies that are missing from our installed version of the Google API Client library.
  • Note that as it's an alpha API it's not in a more recent version so there's no need to upgrade the client library.
  • Use the google-apis-client-generator to generate the code - note that @aaemnnosttv has already generated a Gist of it, which can be used.
• [x] Create and require the new local Composer package packages/apiclient-services-adsenselinks.
  • Copy the necessary generated files into the package.
  • Tweak PHP Scoper rules as needed to ensure the namespaced version of the package works correctly.
  • Add the package as a dependency to the main composer.json file.
  • See this PR for the previously created packages/apiclient-services-subscribewithgoogle for an example.
• [x] Create the class Google\Site_Kit\Modules\Analytics_4\GoogleAnalyticsAdmin\AdSenseLinksService This can follow the example of an existing service, say PropertiesEnhancedMeasurementService.
• [x] Copy the usage of Google_GoogleAnalyticsAdminV1alphaAdSenseLink from the generated Google_Service_GoogleAnalyticsAdmin class into the AdSenseLinksService class.

Test Coverage

• No test coverage needed here; these can be tested in an integrated test when used in a subsequent issue. However, please do verify the code does indeed work as expected.

QA Brief

• This does not introduce any user facing changes and only adds infrastructure for subsequent works. No QA needed here.

Changelog entry

• Add PHP client library for Analytics AdSense links.

[eugene-manuilov]

IB ✔️

[mxbclang]

Unassigned from @10upsimon as he's been ill and we need him focusing on some other work, so anyone else can feel free to pick up, please!

[wpdarren]

Moved to approval as per Slack conversation.