tests: Test serialisation as part of deserialisation fuzzing. Test round-trip equality where possible. Avoid code repetition.
Summary: This is a backport of Core PR17225
Test Plan:
cmake -GNinja .. -DENABLE_SANITIZERS="address;fuzzer" -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ ninja fuzz-addrman_deserialize src/test/fuzz/addrman_deserialize
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Differential Revision: https://reviews.bitcoinabc.org/D8305