Added fuzzers for libbtcore

This patch adds following fuzz targets: btcore_device_class_fuzzer, btcore_property_fuzzer and btcore_module_fuzzer

Test: ./btcore_device_class_fuzzer
Test: ./btcore_property_fuzzer
Test: ./btcore_module_fuzzer
Bug: 189053389

Change-Id: Ibfd5f126b05309c995cdd062f158eb619f32c7a4