make+scripts+docs: update fuzzing script and make fuzz

[babinchak]

Change Description

Update Makefile and scripts/fuzz.sh to use new fuzz testing migration. Moved to separate PR by request Dependent on #6784 Update docs

Steps to Test

run make fuzz fuzztime=1s to run every fuzz test for 1 second See docs/fuzz.md for further documentation

Pull Request Checklist

Testing

• [ ] Your PR passes all CI checks.

Code Style and Documentation

• [x] The change obeys the Code Documentation and Commenting guidelines, and lines wrap at 80.
• [x] Commits follow the Ideal Git Commit Structure.

[lightninglabs-deploy]

@crypt-iq: review reminder