Adding a sample fuzzer using fuzz_service

fuzz_service is now enabled for rust backends. Adding an example fuzzer
which fuzzes a test service.

Bug: 256874936
Test: m example_service_fuzzer && adb sync && adb shell data/fuzz/x86_64/example_service_fuzzer/example_service_fuzzer
Change-Id: Ifd2b16f92c6a5a735ff21b761ae2c0fe132a232d