refactor: Move out utilities from resharding_v3 test loop (#12601)

The resharding V3 test loop became a beast of a file rather quickly.

This PR simply moves some utility functions outside of the test into
three other files, grouped by theme:
- `receipts.rs` for all things about checking receipts existence
- `sharding.rs` for everything related to shards and shard layout
- `trie_sanity.rs` for the new TrieChecker implemented by
@marcelo-gonzalez

Hopefully this will make the method more reusable.

`TestReshardingParameters` is not touched. It still needs improvements
though.