Add "generate_mipmap" font import option.
Add some missing features to the Sprite3D.
Move BiDi override code from Control to TextServer.
Add functions to access TextServer font cache textures.
Add MSDF related flags and shader to the standard material.
Change standard material cache to use HashMap instead of Vector.
-Allows displaying custom options for specific file format variants
-Added support for scene format import to retrieve custom options
This PR is necessary for #54886 to be implemented properly.