Fuzzing enhancements

[benalleng]

With the fuzzer MVP merged in with #1310 there are a few things that we can still improve.

• Ensure there are no artifacts left from the simplification in Introduce fuzzing for payjoin #1153 as pointed out in the code reviews
• Add a CI job for some fuzzing as described in Add Fuzzing CI job on pull requests to confirm it functions properly #1313
• Explore additional engine options and their tradeoffs instead of blanket adding all of them. Any long term fuzzer on enterprise hardware will likely need some babying anyways so the fuzzer that exists in source is mostly for devs to validate tests.
  • These include afl++ and honggfuzz both engines have been tested in the POC but are not really ready at this time with some upstream blockers and questions on their benefits over cargo-fuzz (libfuzzer)
• Add new fuzzing candidates per Tracking fuzzing candidates #1267
• Add arbitrary crate to enhance fuzzing capabilities in Introduce arbitrary crate #1662