Show owner/repo:branch in PR header instead of owner:branch (#8276)

* Initial plan

* Initial plan for showing owner/repoName in PR header

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

* Update PR header to show owner/repoName:branch instead of owner:branch

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

* Revert unrelated change to vscode.proposed.chatParticipantAdditions.d.ts

* Simplify PR header change to only modify display layer

Instead of modifying GraphQL queries and utils, construct the owner/repo:branch format directly in the PR overview and activity bar view provider using existing owner, name, and ref properties from GitHubRef.

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

* Revert unrelated @types changes

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

* Fix repo name

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/github/activityBarViewProvider.ts

@@ -253,10 +253,10 @@ export class PullRequestViewProvider extends WebviewViewBase implements vscode.W
 				state: pullRequest.state,
 				isCurrentlyCheckedOut: isCurrentlyCheckedOut,
 				isRemoteBaseDeleted: pullRequest.isRemoteBaseDeleted,
-				base: pullRequest.base.label,
+				base: `${pullRequest.base.owner}/${pullRequest.base.name}:${pullRequest.base.ref}`,
 				isRemoteHeadDeleted: pullRequest.isRemoteHeadDeleted,
 				isLocalHeadDeleted: !branchInfo,
-				head: pullRequest.head?.label ?? '',
+				head: pullRequest.head ? `${pullRequest.head.owner}/${pullRequest.head.name}:${pullRequest.head.ref}` : '',
 				canEdit: canEdit,
 				hasWritePermission,
 				mergeable: pullRequest.item.mergeable,

src/github/pullRequestOverview.ts

@@ -318,10 +318,10 @@ export class PullRequestOverviewPanel extends IssueOverviewPanel<PullRequestMode
 				canRequestCopilotReview: copilotUser !== undefined && !isCopilotAlreadyReviewer,
 				isCurrentlyCheckedOut: isCurrentlyCheckedOut,
 				isRemoteBaseDeleted: pullRequest.isRemoteBaseDeleted,
-				base: pullRequest.base.label,
+				base: `${pullRequest.base.owner}/${pullRequest.remote.repositoryName}:${pullRequest.base.ref}`,
 				isRemoteHeadDeleted: pullRequest.isRemoteHeadDeleted,
 				isLocalHeadDeleted: !branchInfo,
-				head: pullRequest.head?.label ?? '',
+				head: pullRequest.head ? `${pullRequest.head.owner}/${pullRequest.remote.repositoryName}:${pullRequest.head.ref}` : '',
 				repositoryDefaultBranch: defaultBranch,
 				status: status[0],
 				reviewRequirement: status[1],