all: clean up overall structure, preparing for path-based

[Francesco4203]

Changes:

• trie/trienode: Remove NodeWithPrev, use Node instead since we will not use the prev value anyway; function for create delete node (hash = 0, for marking deleted nodes)
• trie/triestate: track changes by node address instead of address hash; function for creating new Set
• trie/database: add block and state changes fields when calling Update(); init cleans cache in the lower database (hashdb) instead of the wrapper database
• trie/tracer, trie: the process of marking deleted nodes will be done in the trie component now, and the tracer just returns the deleted nodes. This change generalized the tracer.

[huyngopt1994]

init cleans cache in the lower database (hashdb) instead of the wrapper database -> Still curious we will have the other cleans cache in Path db or not.