Like the HID, Audio and Storage subsystem, the Graphics subsystem (which
handles GPUs technically) exposes unix device files (typically in /dev).
To ensure consistency across the repository, move all related files to a
new directory under Kernel/Devices called "GPU".
Also remove the redundant "GPU" word from the VirtIO driver directory,
and the word "Graphics" from GraphicsManagement.{h,cpp} filenames.
The Multiboot header stores the framebuffer's pitch in bytes, so
multiplying it by the pixel's size is not necessary. We ended up
allocating 4 times as much memory as needed, which caused us to overlap
the MMIO reserved memory area on the Raspberry Pi.
The MemoryManager now works, so we can use the same code as on x86 to
map the framebuffer. Since it uses the MemoryManager, the initialization
of the BootFramebufferConsole has to happen after the MemoryManager is
working.
The BootFramebufferConsole highly depends on using the m_lock spinlock,
therefore setting and changing the cursor state should be done under
that spinlock too to avoid crashing.
Instead of seeing a black screen until GraphicsManagement was fully
initialized, this allows us to see the console output much earlier.
So, if the bootloader provided us with a framebuffer, set up a console
as early as possible.
