Use relative filename in picker

[Xethron]

When trying to select a file using #file:<tab>, the picker comes up listing all files in the project with their full file name.

eg: /Users/Xethron/Code/github.com/CopilotC-Nvim/CopilotChat.nvim/README.md instead of just README.md.

This makes it hard to see deeply nested file names, especially on a smaller screen with a smaller picker.

Would be great if this could instead show relative paths in the picker, since they already work in the chat.

[kiet-ap]

yes