Invoke with `bricks sync SRC DST`.
In bundle context `SRC` and `DST` arguments are taken from bundle configuration.
This PR adds `bricks bundle sync` to disambiguate between the two.
Once the VS Code extension is bundle aware they can again be consolidated.
Consolidating them today would regress the VS Code experience if a
`bundle.yml` file is present in the file tree.
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