In order for #1613 to use the Archiver, the Archiver needs to have the context of all layer parents in Apply, Diff and WriteDiff.

I propose changing the interface of these from:

func Apply(ctx context.Context, root string, r io.Reader) (int64, error) {

to:

func Apply(ctx context.Context, mounts []mount.Mount, r io.Reader) (int64, error) {

etc for Diff and WriteDiff

@dmcgowan @crosbymichael @stevvooe

I can do this in #1613 or it can be done separately and I can rebase on it.

Slightly separate, though should be considered as well, these functions will also need context to know if it is an LCOW layer or a Windows Container layer, as the LCOW diff/apply etc are routed to the UtilityVM. If []mount.Mount is used, this context can be provided in the form of the mount type (windows-layer vs lcow-layer)