Insure transaction atomicity

[Erigara]

As part of implementing runtime validator RFC (#3615) we need to make sure that if isi returns error no changes was made to wsv.

Some guardrails could be added to ensure that hash(wsv_before) == hash(wsv_after_error).

[Erigara]

Currently isi like Pair, Sequence might cause problem because if one of their innerinstructions will fail changes from previous instructions won't be roll-backed (so they lack atomicity).

[Erigara]

Also Transaction in general lack atomicity.

[Erigara]

There is two ways to achieve atomic transactions:

1. Cheep wsv clone where transaction will be executed on cloned wsv and either clone will replace original wsv or clone will be discarded;
2. Introduce rollback for transaction when in case of failure any previously executed instructions will be reverted.