Add a fuzzing test harness and fuzz some important components

We'd like to expand our testing to support some fuzzing of important components such as befp.

Tasks

- set up fuzzing in the project
- set up a CI fuzzer that can run during ci_release and independently for a given `fuzztime`
- ensure we can create and store corpus data with the fuzzers
- ensure "found" errors from fuzzing runs can be retrieved on a failure and saved to the corpus
- allow fallback to unit test when run in normal test mode

Then write some more complex fuzz data generators for areas such as:

- Share eds test / Rand
- BadEncodingFraudProof Validate Function (bad_encodings.go)