fuzz-bus-message: add fuzzer for message parsing
    
    As with other fuzzers, SYSTEMD_FUZZ_OUTPUT=1 and SYSTEMD_LOG_LEVEL=debug can be
    used for debugging.
    
    (cherry picked from commit 56b560c26339c4b282c06038316a91509eae75fd)
    
    Resolves: #1696224
    
    patch_name: 0160-fuzz-bus-message-add-fuzzer-for-message-parsing.patch
    present_in_specfile: true
    location_in_specfile: 160
    squash_commits: true