tests: Add fuzzing harness for strprintf(…)
Summary:
Add fuzzing harness for strprintf(…). Update FuzzedDataProvider.h. Avoid hitting some issues in tinyformat (reported upstreams in c42f/tinyformat#70).
Backport of core PR18009.
Test Plan:
ninja bitcoin-fuzzers ./src/test/fuzz/strprintf
Reviewers: #bitcoin_abc, deadalnix
Reviewed By: #bitcoin_abc, deadalnix
Differential Revision: https://reviews.bitcoinabc.org/D8004