tests: Add fuzzing harness for various functions consuming only integrals

Summary:

Add fuzzing harness for various functions consuming only integrals.

Backport of core PR17109.

The missing corpora change in not needed for us.

Test Plan:

ninja bitcoin-fuzzers
./test/fuzz/test_runner.py <path_to_corpus>

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D8142