Adds fuzzers for libmediautils

This change adds fuzzers for a few classes in libmediautils.

Test: Ran on Pixel 3a device for a short period. Estimated coverage is 2.94%.
Signed-off-by: Dylan Katz <dylan.katz@leviathansecurity.com>
Change-Id: I147122092659206800d92c4ebd373f692ea1bdb3