Move mediaswcodec process to apex

bug: 127499775
test:
- adb shell lshal debug android.hardware.media.c2@1.0::IComponentStore/software
check all software c2 codecs are still listed
- clean-built image shouldn't have mediaswcodec in /system/bin
- atest CtsMediaTestCases -- --module-arg CtsMediaTestCases:size:small

Change-Id: I649ba743b9fc82445e5f1e2ad44247e4a3392e4c