Add support for resolution alignment during encoding

[DanielNovak]

This PR adds two new encoder factories:

• SimulcastAlignedVideoEncoderFactory
• DefaultAlignedVideoEncoderFactory

These should be generally always preferred to be used instead of the default SimulcastVideoEncoderFactory and DefaultVideoEncoderFactory. The difference is that the new factories allow to specify a resolution alignment requirement (resolutionAdjustmentin the constructor). HW encoders for VP8 (and H264) require a 16x16 aligned resolutions.

This code is based on the original source from:
https://github.com/shiguredo/sora-android-sdk/blob/3cc88e806ab2f2327bf3042072e98d6da9df4408/sora-android-sdk/src/main/kotlin/jp/shiguredo/sora/sdk/codec/HardwareVideoEncoderWrapperFactory.kt
Credit and thanks go to Shiguredo, Inc.

This is especially a problem while simulcasting - webrtc computes the resolutions based on the scaleResolutionDownBy defined in RtpParameters.Encodings and these resolutions are not 16x16 and this leads to various hard to debug problems with the encoder. WebRTC allows you to override the getEncoderInfo() in HardwareVideoEncoder.java and define the alignment but in most cases it will not crop the resolution and instead it will just adjust the scaleResolutionDownBy you defined. This behaviour is defined here. So from 1, 2, 4 (full, half, quarter resolution) it can create 1, 1, 1 to match the alignment and this is not a correct approach. In our tests the encoder would not work correctly and would drop frames in simulcast scenarios (1280x720, 3 simulcast layers - 1, 2, 4. This breaks if you are stream with phone oriented to left-orientation on Pixel devices).

Relevant issues:
https://bugs.chromium.org/p/chromium/issues/detail?id=1084702
https://bugs.chromium.org/p/chromium/issues/detail?id=1351371
https://bugs.chromium.org/p/webrtc/issues/detail?id=12328

[skydoves]

Overall looks good to me. Nicely done!