This adds trie crate testing using genesis block. It does the following:
- Create the state trie for genesis block, and check it matches.
- Do a fuzzy testing, randomly remove half of the items in the trie. Check that the
database is exactly the same as building the other half from scratch. (This checks GC
works for the first time.)
- Again, then remove the other half of the item in the trie. Check that the result
database is empty. (This checks GC works for the second time.)