Murisi/alternative txs

[murisi]

The objective is to (with as little change as possible) make Namada transactions signable on hardware constrained wallets by making them smaller. The approach to this taken in this branch is to replace inner transactions (amongst other objects) with their hashes, and then only attach the encrypted payloads at the top level.

More precisely, the following changes have been made:

• Removed the inner_tx field of WrapperTx leaving behind tx_hash
• Added an inner_tx field to Tx representing an attached encrypted inner transaction
• The ledger now decrypts and checks the attached inner_tx field against the Wrapper::tx_hash field

The implications of these changes are:

• No encryption is required for/before the signing process (and hence on hardware wallets) because the signature for a WrapperTx is over the hash of an unencrypted Tx

[murisi]

pls update wasm

[murisi]

pls restart ci