Refactor Animation Export rendering code and HDR video support

1. Remove 'video' impex plugin. Now the exporting classes are built in into animationrenderer plugin. It allows us not to pass the options via untyped KisPropertiesConfiguration, but via a type-safe and compiler-tracked KisAnimationRenderingOptions.

2. Add options for configuring HDR video encoding with HEVC (H265) codec

3. When HDR video option is activated, then PNG export filter is automatically forced to output HDR PNG files (see a hack in DlgAnimationRenderer:: getFrameExportFilterConfiguration())

4. !!! Rendering dialog now supports relative paths for video and frame export locations. As a base it uses either document location, or the location of animation/frames, if it is present and absolute.