Feature request: Group filters

Hi,
Is there a way to apply multiple filters at once?
For example, when I want to use 3 filters simultaneously:
```
TransformationOptions.Builder()
.setVideoFilters(listOf(ContrastFilter(3f), BrightnessFilter(0.7f), SaturationFilter(0f)))
```
Only the last filter is applied to the transformation (target video) and previous ones are lost.

Does the library support it?

These examples [GlFilterGroup](https://github.com/MasayukiSuda/ExoPlayerFilter/blob/master/epf/src/main/java/com/daasuu/epf/filter/GlFilterGroup.java), [GlFilterGroup](https://github.com/MasayukiSuda/Mp4Composer-android/blob/master/mp4compose/src/main/java/com/daasuu/mp4compose/filter/GlFilterGroup.java) and [GPUImageFilterGroup](https://github.com/cats-oss/android-gpuimage/blob/master/library/src/main/java/jp/co/cyberagent/android/gpuimage/filter/GPUImageFilterGroup.java) might be helpful and used as a reference.

Thank you 👍

Start at TransformationOptions.Builder().setVideoFilters and trace how the video filter list is passed into the transformation. Review the linked GlFilterGroup and GPUImageFilterGroup implementations for composition patterns, then verify that contrast, brightness, and saturation all apply in order without earlier filters being discarded.

Written by the indexing model from the issue text.