Feature/compliance

[EvgenKor]

These changes are required to generate detailed compliance report within the client library. Added following routines in the wasm library:

• extract_decrypt_keys to get symmetric cipher keys needed to decrypt output tx items (account and notes)
• symcipher_decrypt_acc \ symcipher_decrypt_acc to decrypt account and notes from the memoblock (needed to verify report correctness during development)
• get_tx_inputs to find transaction inputs for the transaction: account and notes and intermediate nullifier from the input account
• calculate_nullifier to getting nullifier from the account
• few helper routines and unit-test for retrieving tx inputs

[EvgenKor]

The PR is ready to review. The branch was merged with dd branch to resolve conflicts

[EvgenKor]

I believe it's better to remove commented code in order to keep the code clean

Sure, I forgot to remove it. Now it's fixed