[testing] Enable integration/fuzz testing for randomly generated transactions

[marun]

• Add a function that enables randomly generating transactions using the wallet
• Add an integration and/or fuzz test that uses the transaction generator to build+verify+accept blocks
• Use the transaction generator for antithesis testing

[github-actions]

This issue has become stale because it has been open 60 days with no activity. Adding the lifecycle/frozen label will cause this issue to ignore lifecycle events.