Moved ZBCManager to `video_core/zbc_manager.cpp/h` for modularity. Added
`gl_zbc_clear.cpp/h` for efficient OpenGL color, depth, and stencil clears.
Updated `RasterizerOpenGL::Clear` to use ZBC with fallback. Added stencil
type validation. Fixed color mask and logging. Updated `CMakeLists.txt`.
Enhances performance and code organization.
Signed-off-by: Zephyron <zephyron@citron-emu.org>