vk: Remove more raw casts

vk: Remove more raw casts

This removes nearly all the remaining raw Anvil<->Vulkan casts from the
C source files.  (File compiler.cpp still contains many raw casts, and
I plan on ignoring that).

As far as I can tell, the only remaining raw casts are:
    anv_attachment_view -> anv_depth_stencil_view
    anv_attachment_view -> anv_color_attachment_view