Introduce ML-based denoiser

[dtarakanov1]

• Update post-effect API
• Introduce ML-based denoiser post-effect
• Denoiser selection via command line args
• Split screen mode when denoising enabled
• Remove denoiser-related ifdef directives
• Cleanup BaikalStandalone code
• Fix GCC-8 build warnings

Authors: achernigin1987, AvKhokhlov, dtarakanov1

[dtarakanov1]

Issues preventing merge:

1. The changes require modified RadeonRays from master branch, while the Baikal requires some adaptation to the latest RadeonRays.
2. The file "Baikal/PostEffects/ML/denoiser.cpp" cannot be compiled with BAIKAL_EMBED_KERNELS=ON.