Add Offscreen Framebuffer support

Vulkan/res/shaders/passthrough.frag

@@ -0,0 +1,11 @@
+#version 450
+
+layout(set = 0, binding = 0) uniform sampler2D texSampler;
+layout(location = 0) in vec2 fragTexCoord;
+
+layout(location = 0) out vec4 outColor;
+
+void main()
+{
+  outColor = texture(texSampler, fragTexCoord);
+}