Protocol 19 support

[juanhurtado10]

ℹ️ This issue is an Epic

Context

Protocol 19 implements two Core Advancement Proposals.

CAP-21 introduces a new suite of transaction preconditions, which are optional requirements you can add to control transaction validity. Time bounds, which have long been a Stellar transaction precondition, allow you to craft transactions that are only valid in a specific time-based window. The new Protocol 19 preconditions allow you to craft transactions that skip sequence numbers, set ledger bounds, enforce relative time and ledger delays (aka "relative timelocks"), and require extra signers (e.g. hash locks).

CAP-40 adds a new signer type that allows multiple parties to build a set of transactions for signing that guarantees if one transaction is signed, authorized, and submitted, information is revealed that allows all other transactions in the set to be authorized as well.

Objective

• To add support for the new Stellar protocol 19

Checklist

• [CAP-0021] Generalized transaction preconditions #158
• [CAP-0040] Ed25519 Signed Payload Signer for Atomic Transaction Signature Disclosure #159