Improve SDK BitmapVideoFilter memory usage

[liviu-timar]

🎯 Goal

When using BitmapVideoFilter, memory usage increases rapidly and the client app crashes. Memory usage should be stable, GC should be able to keep up.

🛠 Implementation details

Refactored YuvFrame:

• Used libyuv to copy YUV planes
• Used buffer rotation insted of bitmap rotation (rotated I420 buffer, which is shorter)
• Cleaned-up memory
• Code structure and naming improvements

Released yuvBuffer in FilterVideoProcessor.

🧠 Memory Usage

Demo app profiling with filter enabled in a call on a Pixel 4
Before: Reached ~4 GB in under 5 mins and crashed
After: Stays in the 360-590 MB range even after 2h. Stable.

🧪 Testing

• Start a call, enable video filter (background blur) and leave call running.
• Needs testing on a lower-end device.
• Needs battery profiling.
• See test results in comments below.

☑️Contributor Checklist

General

• I have signed the Stream CLA (required)
• Assigned a person / code owner group (required)
• Thread with the PR link started in a respective Slack channel (required internally)
• PR targets the develop branch

Code & documentation

• Changelog is updated with client-facing changes

☑️Reviewer Checklist

• New feature tested and works

🎉 GIF

[liviu-timar]

Same call, original blur (without PorterDuff compositing): both phones in call for over 2h.