Resolve insteadOf URL aliases in remaining remote-parsing call sites

[Copilot]

With a global git config like url.https://github.abc.com/.insteadOf=github:, git clone github:org/repo leaves github:org/repo as the literal remote URL. The extension would fail to recognize the host and get stuck configuring remotes.

resolveGitUrl + parseRepositoryRemotesAsync (which apply url.<base>.insteadOf substitutions before parsing) already existed, but only two call sites in FolderRepositoryManager had been migrated. Several other paths still used the sync parseRepositoryRemotes and silently dropped aliased remotes.

Changes

• folderRepositoryManager.ts — createGitHubRepositoryFromOwnerName now awaits parseRepositoryRemotesAsync; dropped the now-unused sync import.
• stateManager.ts — setIssueData uses the async variant for enterprise-remote detection (affects which auth provider is selected for issue queries).
• pullRequestGitHelper.ts — createRemote and getUniqueRemoteName (promoted to async, sole caller already awaited) use the async variant, so PR-checkout's dedup and unique-name logic sees aliased remotes.
• src/test/common/remote.test.ts — new unit tests covering basic insteadOf substitution, longest-prefix selection on overlapping aliases, and the no-match passthrough.

Intentionally not migrated

ReviewManager state-change comparison and PostCommitCommandsProvider.getCommands remain on the sync variant — both are synchronous VS Code API surfaces and neither is on the failing setup path; switching them would require larger refactors for no user-visible benefit here.

Note

This is an extension-side mitigation for the underlying upstream gap tracked at microsoft/vscode#174941; if the git extension begins surfacing the resolved URL directly, the resolveGitUrl helper can be retired.