Improve DX for Predicate class

[arboleya]

It should follow the same DX we have on Contract, supporting things like:

• txParams
• callParams
• getTransactionRequest
• Etc.

This increases flexibility and ease of use, giving users complete control of everything.

Related:

• Implement getTransactionId for transfers on the Predicate class #1451
• Improve DX for Script class #1458

[arboleya]

Pasting more insights from the 8th item from here:

• Feedback - WebAuthn App QA Results #1545

There is no prestaging of txs, i.e. if I use predicate.transfer, I can't see the tx_id unless I construct things manually, consider a prestage like predicate.prepare.transfer so that we can see the final tx before we send. I know this is already being considered.

[arboleya]

Postponed until we sort out the breaking change it will cause.