Fail on missing clone

[olidal]

Adds new option --no-full-clone to syncoid:

--no-full-clone
Only applies to recursive transfer when clone handling is active.
In case a clone origin is missing (on destination) because its transfer was interrupted don't switch to a full clone sync.
Example worst case scenario this may help prevent:
A 1TB dataset has 500 identical clones. Overall it uses just 1 TB storage space at the source, because all clone share the storage with origin.
Assume a recursive transfer is started that needs to send all datasets (origin and 500 clones).
Assume also the origin dataset transfer ends up failing. Without selecting this option, the recursive transfer proceeds to next recursive dataset, and because origin is missing (receive not completed), each clone becomes a full clone and we end up trying to transfer 500TB !

[phreaker0]

it would be nice to have an improved clone handling like #572 instead of a workaround like this, but because this is very simple we can add it for now until we have proper clone handling with dependency handling.