codec2: move AVAFactory code from external/v4l2_codec2 to vendor/google_arc

C2AVAFactory is strongly ARC-related code which depends on some ARC libraries,
it should not be placed under external/v4l2_codec2. Moreover,
external/v4l2_codec2 does not have pi-arc-dev branch so we could not handle the
library difference between pi-dev and pi-arc-dev.

We move C2AVAFactory to vendor/google_arc and provide the united API for codec2
component's usage. By doing so we could keep other codec2 codes unchanged and
are able to handle both pi-dev and pi-arc-dev.

Note that this change should be uploaded after the vendor/google_arc change is
merged to pi-arc-dev.

Bug: 110177751
Test: build cheets image on pi-arc-dev
Test: vendor/google/build/build_test.bash on pi-dev

Change-Id: Ib3fd6a55bd587be9340232903438e314e4f55c3f