check-commitment-hist-at-blk-range: support empty blocks, sampling logic extraction

[AskAlexSharov]

• relax check when several empty blocks (same state root)
• sampling logic extraction

for blockNum := range sampler.BlockNums(from, to) {

or

for start := fromBlock; start <= toBlock; start += chunkSize {
	if sampler.CanSkip() {
		continue
	}

Also:

• enable CommitmentHistVal by default - with --sample support

[sudeepdino008]

do we need this loop and check for empty blocks?
we can just compare with header stateroot hash and be done. That's enough check.

[AskAlexSharov]

added

[sudeepdino008]

wait, i still see the "verify gap blocks" logic
I don't think we need checks for empty blocks? is it adding anything? we can remove it and keep things simple.

[AskAlexSharov]

1. we don't know "are they really empty?" - need proof by headers root compare
2. even if "empty blocks" are real - we still need to check: that our StateHistory doesn't have any history events in this blocks.