Add max fee to payment params

[TheBlueMatt]

We really need this, kinda dumb that we don't have it. Luckily it's trivial.

[TheBlueMatt]

Also we should rip out the 10% check in the retry code which was really just a buggy code check, but that should happen later.

[tnull]

Closing, as this is a duplicate of #2339