build/vulkan: split vulkan gir

docs/libs/vulkan-wayland/index.md

docs/libs/vulkan-wayland/sitemap.txt

docs/libs/vulkan-xcb/index.md

docs/libs/vulkan-xcb/sitemap.txt

docs/libs/vulkan/index.md

docs/libs/vulkan/sitemap.txt

docs/meson.build

gst-libs/gst/vulkan/meson.build

gst-libs/gst/vulkan/vulkan_fwd.h

gst-libs/gst/vulkan/vulkan_mkenum.py

gst-libs/gst/vulkan/wayland/wayland.h

gst-libs/gst/vulkan/xcb/xcb.h

pkgconfig/gstreamer-vulkan-uninstalled.pc.in

pkgconfig/gstreamer-vulkan-wayland-uninstalled.pc.in

pkgconfig/gstreamer-vulkan-wayland.pc.in

pkgconfig/gstreamer-vulkan-xcb-uninstalled.pc.in

pkgconfig/gstreamer-vulkan-xcb.pc.in

pkgconfig/gstreamer-vulkan.pc.in

pkgconfig/meson.build