Feature/1187 Read EXR files from memory

[nabielkandiel]

Issue for reference https://github.com/f3d-app/f3d/issues/1187

Below is an image of what currently happens when reading a .usda file in f3d

This is what it looks like on this branch

file is pulled from here https://github.com/mwestphal/assets/tree/main/full_assets/StandardShaderBall

Please note you have to change some options in the cmake build files to enable USD and EXR CMakeLists.txt line 58 turn on module_exr plugins/CMakeLists.txt line 6 turn on build_usd

MemStream is a private class created inside F3DEXRReader, this is needed as Imf::RgbaInputFile needs an input that has stream like functionality or is derived from Imf::IStream https://openexr.com/en/latest/ReadingAndWritingImageFiles.html#low-level-i-o

I'm not sure if this is the best design choice to have it be a private class, i can change that if desired but im not sure if any other class is going to need to use this functionality.