Added basicmbr_fuzzer

The following are the updates to the fuzzer:
1. Randomized APIs & Parameters
2. Added New APIs to the fuzzer
3. Improved Coverage of basicmbr.cc from 20% to 70%

Test: ./basicmbr_fuzzer corpus/
Bug: 332255733
exec/s: 30

Change-Id: I67aa29514d4f24fb0d2ae7e8f22d7fe5e2dfe17d