07803f501e
These are API improvements on the way to solving https://github.com/flutter/flutter/issues/131182. * Remove `effect_transform` and `is_subpass` from the static `FilterContents` factories. These are for internal use only. * Replace `impeller::Paint` filter procs with Aiks `ImageFilter` factories similar to `ColorFilter`. This gives Aiks a simple interface for constructing filters and prevents possible state cloning bugs when copying filters into `EntityPass`. * Allow for setting filter inputs, setting the effect transform, and enabling subpass mode on a filter chain after it has been instantiated. This will allow us to sample coverage in `EntityPass` without rendering any snapshots using rect filter inputs.