Filesystem sharing here means the ability to share some parts of the
host filesystem with the guest. It's mostly about sharing files and
container bundle root filesystems.
In order to allow for different file and rootfs sharing implementations,
we define a FilesystemSharer interface.
This interface provides a preparation step, where concrete
implementations will be able to e.g. prepare the host filesysstem.
Then it provides 2 methods, one for sharing any file (regular file or a
directory) and another one for sharing a container root filesystem
Signed-off-by: Samuel Ortiz <s.ortiz@apple.com>
