Tool to verify similarity of FS and Trie

[exalate-issue-sync]

After FS is created, it is nice to have tool to verify that it has the same data as Trie.

We can compute state root based on FS. Likely it will be quickly enough.

We can consider RocksDB snapshot feature which allows to access data on top of some block. Maybe even col.iter() works.

[Longarithm]

Some ideas:

• verify only state of account - if we observed FS data corruption, it may be easier to check each modified account in state
• current impl will work with offline dump and we can add a trigger to check similarity, say, each day. Here we also need to rely on col.iter() fixing contents of flat storage

[Longarithm]

Marcin' work on this in the scope of fast state sync idea: #8531
We can iterate over trie and flat storage simultaneously and check each single key, though state root computation by flat storage would be faster.

[Longarithm]

Done in #8531