Implements recursive glob-based file search for both suggestions and execution of the `@` command.
- When typing `@filename`, suggestions will now include files matching `filename` in nested directories.
- Suggestions are sorted by path depth (shallowest first), then directories before files, then alphabetically.
- The maximum recursion depth for suggestions is set to 10.
- When executing an `@filename` command, if the file is not found directly, a recursive search (using the glob tool) is performed to locate the file.
This addresses the first request in issue #461 by allowing users to quickly reference deeply nested files without typing the full path. Also addresses b/416292478.
This commit resolves a bug where the `write-file` operation could fail to render content due to a missing filename.
The fix involves:
- Ensuring `fileName` is consistently passed to `DiffRenderer.tsx` through `ToolConfirmationMessage.tsx`, `ToolMessage.tsx`, and `useGeminiStream.ts`.
- Modifying `edit.ts` and `write-file.ts` to include `fileName` in the `FileDiff` object.
- Expanding the `FileDiff` interface in `tools.ts` to include `fileName`.
Additionally, this commit enhances the diff rendering by:
- Adding syntax highlighting based on file extension in `DiffRenderer.tsx`.
- Adding more language mappings to `getLanguageFromExtension` in `DiffRenderer.tsx`.
- Added lots of tests for all the above.
Fixes https://b.corp.google.com/issues/418125982
