core: Add context when calling to activate Storage Domain

Add context when calling to activate Storage Domain from Attach Storage
Domain so the locks will be transferred to the internal command

Change-Id: I38f8992a5336ac193a16dda08c5214c2315829a5
Bug-Url: https://bugzilla.redhat.com/1150075
Signed-off-by: Maor Lipchuk <mlipchuk@redhat.com>