Ensure txn are consensus/standard valid

[ariard]

Right now we have failure applying this test hardening patch, some of our generated transactions don't have a minimal relay fee.

Fixing this while reworking our fee logic for anchor outputs.

See : TheBlueMatt@34daef5

[ariard]

We should check that our counterparty can't malleate our commitment transaction in such a way that it's not valid with regards to standardness or consensus rules.