[backport#18417 2/3] tests: Add fuzzing harness for functions in timedata.h

Summary:
https://github.com/bitcoin/bitcoin/pull/18417/commits/43ff0d91f8a4af68e64fd12273133322d44a69ea

Depends on D7133

Partial backport of Core PR18417

Test Plan:

cmake -GNinja .. -DENABLE_SANITIZERS="address;fuzzer" -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
ninja bitcoin-fuzzers
./src/test/fuzz/timedata

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D7134