Murisi/restructure tx merge

[murisi]

This is an attempt to achieve #1255 with the tip of main merged in. Overall the main changes introduced by this branch are:

• Instead of having an outer transaction structure containing an inner transaction, there is now a single transaction structure containing a flat list of sections.
• Instead of wrapping inner transactions in a structure that supplies a signature, the unsigned data is added as a section to the transaction at the same level as it corresponding signature section.
• The WASM code now receives a Tx object instead of a data byte vector. This is because the data section's signature is stored in a different section, and because the extra data also resides in a separate section.
• Encryption is now done separately after all signing is complete - in particular this means that there are no longer any signatures over encrypted data.
• Upgraded the MASP client and validation code to use the latest MASP crate.
• Added a builder section to Txs where the auxiliary inputs that were used to construct a MASP transaction can be stored. This may be useful for hardware wallets when validating a given Transaction object.

Additional notes:

• Also addressed the issues in Unsafe MASP Transaction Validation #1374 .
• The MASP E2E tests yield false negatives in the CI. See: MASP CI False Positives and Negatives #1376

[murisi]

I've merged in base in 82961de which should fix the failing jobs in CI

Thanks, this merge is fine. However, if I remember correctly the only failing jobs in the CI were due to the 3 MASP E2E tests failing, and I identified that to be due to the CI configuration. See #1376 .

That being said, there are some E2E tests (that are not executed by the CI) that are failing for me locally:

failures:
    e2e::eth_bridge_tests::test_unauthorized_tx_cannot_write_storage
    e2e::multitoken_tests::test_multitoken_transfer_established_to_established
    e2e::multitoken_tests::test_multitoken_transfer_established_to_implicit
    e2e::multitoken_tests::test_multitoken_transfer_implicit_to_established
    e2e::multitoken_tests::test_multitoken_transfer_implicit_to_implicit

Do you have any ideas on what might be the cause? Thanks!

[murisi]

Subsumed by #1462 .