Agents - adopting etags for additional REST API calls

[lszomoru]

No description provided.

[Copilot]

Pull request overview

This PR updates the Agents window’s GitHub integration to use ETag-aware REST responses (request2) for more calls, enabling conditional requests and reducing unnecessary payloads when data hasn’t changed.

Changes:

• Switch repository and CI check-run fetchers/models to use request2 and carry ETags through refresh cycles.
• Update PR comment posting and check-run annotation fetching to use request2 response shapes.
• Adjust browser tests/mocks to assert against { data, statusCode, etag } responses.

Show a summary per file

File	Description
src/vs/sessions/contrib/github/test/browser/githubModels.test.ts	Updates mock fetcher signatures to match ETag-aware response shape.
src/vs/sessions/contrib/github/test/browser/githubFetchers.test.ts	Updates assertions for the new { data, statusCode } fetcher return values.
src/vs/sessions/contrib/github/browser/models/githubRepositoryModel.ts	Caches repository ETag and performs conditional refreshes.
src/vs/sessions/contrib/github/browser/models/githubPullRequestCIModel.ts	Caches checks ETag and performs conditional refreshes for check runs.
src/vs/sessions/contrib/github/browser/fetchers/githubRepositoryFetcher.ts	Moves repository REST call to request2 and returns IGitHubApiResponse.
src/vs/sessions/contrib/github/browser/fetchers/githubPRFetcher.ts	Uses request2 for posting PR/issue comments and validates presence of response data.
src/vs/sessions/contrib/github/browser/fetchers/githubPRCIFetcher.ts	Uses request2 for check runs, reruns, and annotations fetching (ETag-enabled for check runs).
src/vs/sessions/contrib/github/browser/fetchers/githubChangesFetcher.ts	Switches compare API call to request2 and maps response data to changed files.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/sessions/contrib/github/browser/fetchers/githubPRFetcher.ts:245

• Same as above for issue comments: request2() can return data: undefined for 204/304 without throwing, so the thrown error should include response.statusCode to aid debugging and to distinguish server behavior changes from client mapping failures.

		const data = response.data;
		if (!data) {
			throw new Error(`Failed to post issue comment to ${owner}/${repo}#${prNumber}`);
		}

• Files reviewed: 8/8 changed files
• Comments generated: 2