Implement support for masked stencil clears on Vulkan (#5589)

* Implement support for masked stencil clears on Vulkan

* PR feedback

src/Ryujinx.Graphics.Vulkan/Shaders/DepthStencilClearFragmentShaderSource.frag

@@ -0,0 +1,8 @@
+#version 450 core
+
+layout (location = 0) in vec4 clear_colour;
+
+void main()
+{
+    gl_FragDepth = clear_colour.x;
+}