Cypress can now sign programmatically

[Tbaut]

closes #357

• can sign/reject Txs
• can see the transactions queue and analyze the payload

todo:

• tests will fail if a tx is the same as one that's in the queue so we need to clean pending TXs first if we want to see the whole flow. I'll do this in another PR, when approving/rejecting pending TXs.

[Lykhoyda]

Overall looks good considering the accept transaction will be handled in the next PR. I requested some changes for code duplication.

[Tbaut]

The accept transaction is definitely working, but under some specific conditions. I'm on the fence between:

• fixing it in the issue I mentioned ([Cypress] Add helper to reject any pending multisig Tx #370)
  or
• actually do it right from the get go (in a separate issue as well), and go with a full setup including forking the network with Chopsticks, running an indexer against this fork, start with a blank page every single test, test the multisig creation flow, and signing a TX. This would probably be ideal, but non trivial, and the sequence in which tests will be run will matter.