Enhancement: Allow including/excluding extended file attributes during restore

Restic restore attempts to restore all extended file attributes.
Now two new command line flags are added to restore to control which
extended file attributes will be restored.

The new flags are `--exclude-xattr` and `--include-xattr`.

If the flags are not provided, restic will default to restoring
all extended file attributes.

https://github.com/restic/restic/issues/5089
https://github.com/restic/restic/pull/5129