[GLSL] Place magic uniforms to uniform buffers

The absence of a plain uniform helps a lot in the case of shared contexts. Plain uniforms are the state of the program object, not the state of the context. In other words, when you modify uniforms through the glUniformXXX functions, you change the state of the program. It is bad when the program is shared between contexts because it's requires additional synchronization. So it would be nice if there was an option like "place_magic_uniforms_to_ubo".

No file or test is identified in the issue. Start by locating the GLSL handling for magic uniforms and the existing uniform-buffer generation, then determine how an option to place those uniforms in a UBO should behave for shared contexts. Done means the option is supported and covered by tests for the generated GLSL.

Written by the indexing model from the issue text.