Display a single trust dialog for bg sessions

[DonJayamanne]

Fixes microsoft/vscode#290947

[Copilot]

Pull request overview

This PR aims to fix issue #290947 by preventing multiple trust dialogs from appearing for background sessions in empty workspaces. The changes introduce a caching mechanism to remember trust decisions for repositories in empty workspaces, avoiding repeated prompts to the user.

Changes:

• Introduced a new caching mechanism (_repositoryCacheInEmptyWorkspace) to store trust decisions for repositories in empty workspaces
• Added getCachedRepository() method to manage repository retrieval with cached trust decisions
• Renamed checkFileExists() to checkPathExists() to better reflect its usage for both files and directories
• Refactored trust verification logic to use the new cached repository method instead of manual .git folder checks
• Updated moveOrCopyChangesToWorkTree() to accept an explicit repository path parameter instead of relying on the active repository
• Removed IFileSystemService parameter from CopilotCLIChatSessionParticipant constructor (no longer needed)

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
src/extension/chatSessions/vscode-node/copilotCLIChatSessionsContribution.ts	Main implementation: added repository caching for empty workspaces, refactored trust dialog logic, renamed utility function, and improved repository retrieval in worktree operations
src/extension/chatSessions/vscode-node/test/copilotCLIChatSessionParticipant.spec.ts	Updated test to remove the now-unused MockFileSystemService parameter from participant constructor

Comments suppressed due to low confidence (1)

src/extension/chatSessions/vscode-node/copilotCLIChatSessionsContribution.ts:802

• Grammar issue: "lets" should be "let's" (contraction of "let us").

		// If we have repo then its trusted, lets get the latest information again by requesting the repo again.