Add "Organization" label for prompt files

[pwang347]

Fixes #280798

[Copilot]

Pull request overview

This PR adds internal support for distinguishing "Organization"-provided prompt files from regular extension prompt files. Prompt files from the built-in chat extension that are located under a /github/ path are now labeled as "Organization" instead of "Extensions" in the UI.

Changes:

• Modified isModeConsideredBuiltIn() to exclude organization-provided modes (those with /github/ in their path) from being considered built-in
• Added grouping logic to separate extension prompt files into "Organization" and "Extensions" categories based on their path
• Removed unused ExtensionAgentSourceType import

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/vs/workbench/contrib/chat/browser/widget/input/modePickerActionItem.ts	Refactored built-in mode detection to exclude organization-provided modes (under /github/ path) and removed unused import
src/vs/workbench/contrib/chat/browser/promptSyntax/pickers/promptFilePickers.ts	Added grouping logic to separate extension prompts into "Organization" and "Extensions" categories, and injected IProductService dependency

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/chat/browser/promptSyntax/pickers/promptFilePickers.ts:447

• The comment "Hack:" suggests this is a temporary solution. Consider documenting this more thoroughly with information about what a more permanent solution would look like, or create a tracking issue for a better implementation. The hardcoded '/github/' path check is brittle and may need to be made more configurable in the future.

		// Hack: if the prompt file comes from the built-in chat extension and is under a `/github/` path it's an organization-provided prompt file.