feat(utils): Implement pick_files()

[cryptomilk]

This implements a file picker, to pick the file you want to execute with the debugger.

Fixes #1130

[cryptomilk]

It looks like this with telescope dap:

[cryptomilk]

Ping?

[mfussenegger]

Pushed a couple of changes:

• Uses vim.fs.dir instead of find/bfs to make it platform independent (but requires nvim 0.11)
• Default executables to true as I think that's the common use case and it allows to use it like program = require("dap.utils").pick_file, in a configuration entry, without wrapping it in another function to provide the arguments.
• Simplified the coroutine logic, given that pick_one is already coroutine aware and the callback is optional.
• Fixed the filter example. It is a lua-pattern, not a glob pattern.
• Added docs to dap.txt

Open questions to me:

• Could re-add find as fallback for nvim 0.10 and earlier.
• Could change the filter from a lua pattern to a glob via vim.glob.to_lpeg() - might be more intuitive given that it is about file paths, but could also be confusing if it is different to pick_process

[cryptomilk]

A fallback for nvim 0.10 would be nice as it just has been released :-)

[mfussenegger]

A fallback for nvim 0.10 would be nice as it just has been released :-)

Ah, I got the numbers mixed. It requires 0.10. The fallback would make it work in 0.9 or earlier.

[cryptomilk]

Ah, I got the numbers mixed. It requires 0.10. The fallback would make it work in 0.9 or earlier.

Ah, then I would argue new feature new nvim version required :-)

[mfussenegger]

Decided to add in the find fallback (but left bfs out). I also changed the result to return dap.ABORT, so it doesn't attempt to start the debug session if one cancels the dialog.