assistant: Add glob matching for `file` slash command (#13137)

This PR adds support for glob matching when using the `file` slash
command inside the assistant panel:


https://github.com/zed-industries/zed/assets/53836821/696612d2-486c-4ab0-bf3c-d23a3eeefd25

Release Notes:

- N/A
d5735dab9aBennet Bo Fenner committed on 6/17/2024, 11:53:27 AM· committed by GitHubparentc793bbd
4 files changedLine totals unavailable