snapshotctl: Support pause/resume of snapshot merge

Add Resume snapshot-merge API.

Bug: 400723109
Test: snapshotctl pause-merge
snapshotctl resume-merge

Change-Id: I92dd3325f2e26127303a828fa01b7632fa730c50
Signed-off-by: Akilesh Kailash <akailash@google.com>
6 files changed