Add a ctx parameter to vfs.New() so callers can pass in context
carrying ConfigInfo and FilterInfo. The context is stripped of
cancellation but config and filter values are preserved into a fresh
background context.
This also
- move in use options (Opt) from vfsflags to vfscommon
- change os.FileMode to vfscommon.FileMode in parameters
- rework vfscommon.FileMode and add tests
Before this change we initialized the rc for a single VFS. However
rclone can have multiple VFSes in use now so this is no longer
adequate.
This change adds an optional fs parameter to all the VFS methods to
disambiguate VFSes when there is more than one in use.
It also adds a method vfs/list to show all the active VFSes.
This adds outline tests for the rc commands which didn't have tests
before.