This header doesn't actually make use of MathUtil.h within itself, so
this can be removed. Many other source files used VideoCommon.h as an
indirect include to include MathUtil.h, so these includes can also be
adjusted.
While we're at it, we can also migrate valid inclusions of VideoCommon.h
into cpp files where it can feasibly be done to minimize propagating it
via other headers.
The path to the MoltenVK library can be specified by the
LIBMOLTENVK_PATH environment variable, otherwise it assumes it is
located in the application bundle's Contents/MacOS directory.
The current approach results in the UI thread creating a graphics device
whilst the core is running, leading to races on function pointers, and
potentially crashing.
Given this is a base class, we should clearly state what the parameters
to the functions in its exposed interface actually mean or represent.
This avoids needing to hunt for the definition of the functions in cpp
files.
While we're at it, normalize said parameter names so they follow our
naming guidelines.
Given that this only contains functions from the VideoBackendBase class,
it makes more sense to move these to the relevant cpp file to keep them
all together.
There's no official implementation of the Vulkan API,
and Dolphin currently isn't set-up to work with the
single, commercially-available third-party implementation.
