C2SoftDav1dDec: improve error handling in outputBuffer()

Add a check that compares picture dimensions against mWidth and mHeight
before copying. Make use of setError at all possible places.

Bug: 436471113
Test: atest MctsMediaV2TestCases -- --module-arg
MctsMediaV2TestCases:instrumentation-arg:codec-filter:="^.*\.decoder$"
--module-arg
MctsMediaV2TestCases:instrumentation-arg:media-type-sel:=av1
Test: VtsHalMediaC2V1_0TargetVideoDecTest
Test: atest MctsMediaDecoderTestCases -- --module-arg
MctsMediaDecoderTestCases:instrumentation-arg:codec-prefix:=c2.android.av1-dav1d.decoder
Flag: EXEMPT bugfix

Change-Id: Id82d83350b1ad8112d02c84023a07c08d929bc1e