tests: Add harness which fuzzes EvalScript and VerifyScript using a fuzzed signature checker

Summary:

Add harness which fuzzes EvalScript and VerifyScript using a fuzzed
signature checker.

Backport of core PR18155.

Test Plan:

ninja bitcoin-fuzzers
./src/test/fuzz/signature_checker <path_to_corpus>

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D8968