[Vulkan] Add resolution scaling support to Vulkan backend.

Largely similar to D3D12 implementation but more simple buffer
management and no mips scaling. Includes both FBO and FSI
rendering paths.

Tested on Linux with 2x2 and 3x3 running smoothly.

src/xenia/gpu/vulkan/vulkan_pipeline_cache.cc

@@ -57,7 +57,9 @@ bool VulkanPipelineCache::Initialize() {
       SpirvShaderTranslator::Features(vulkan_device),
       render_target_cache_.msaa_2x_attachments_supported(),
       render_target_cache_.msaa_2x_no_attachments_supported(),
-      edram_fragment_shader_interlock);
+      edram_fragment_shader_interlock,
+      render_target_cache_.draw_resolution_scale_x(),
+      render_target_cache_.draw_resolution_scale_y());
 
   if (edram_fragment_shader_interlock) {
     std::vector<uint8_t> depth_only_fragment_shader_code =