Rework how files are excluded

[mieubrisse]

Right now, fd's default "exclude files that are in the .gitignore directory" can lead to unexpectedly empty results if you cd into one of the files in the .gitignore directory and try to use cmdk to find stuff inside the directory.

Ideally, we'd disable fd's "exclude .gitignore results", and then choose our own exclude paths to pare down the results to a reasonable size (so cmdk isn't operating on ginormous lists of files even across the entire filesystem).

[mieubrisse]

Also, we should include the excluded directory itself, but not the children, so the user can jump into it as desired. This is particularly useful when doing a cmdk -o, so the user isn't confused by why a directory is missing (e.g. node_modules)