thin: enhance lvcreate error paths

thin: enhance lvcreate error paths

Improve error response and reporting, when creating thin snapshots.
If the thin pool kernel metadata already have device with ID lvm2
tries to create, give more meanigful error message and also properly
restore transaction id to the value known to thin-pool in this case.

Before it's been possible to divert by one from kernel TID value,
and lvm2 stacked delete message for such thin device.