Before:
```
shreyas.goenka@THW32HFW6T deco-538-pipeline-error % bricks bundle deploy
Error: both myNb.py and myNb.sql point to the same remote file location myNb. Please remove one of them from your local project
```
Even though myNb.sql was created by renaming myNb.py
Now deployments are successful
This moves `git.FileSet` to `libs/fileset` and decouples it from the Git package.
It is made aware of gitignore rules in parent directories up to the
repository root as well as gitignore files in underlying directories
through the `fileset.Ignorer` interface.
The recursive directory walker is reimplemented with [filepath.WalkDir].
Follow up to #182.
The code depended on the project package for:
* git.FileSet in the watchdog
* project.CacheDir to determine snapshot path
These dependencies are now denormalized in the SyncOptions struct.
Follow up for #173.
Pieter Noordhuis
shreyas-goenka
Fabian Jakobs