apexer: Add --do_not_check_keyname

For some apexes(e.g. VNDK apex for current version), the apex name is
determined dynamically. To support this scenario, apexer can just ignore
given key filename(--key).

Test: m com.android.vndk.current
Change-Id: Ibe0cd1dac1367d397820dd582a92f05e050f4a46
1 file changed