Added usage hint for --auto-sampled-textures, added test cases

Test/glsl.autosampledtextures.frag

@@ -0,0 +1,13 @@
+#version 460
+
+layout (location = 0) in vec2 in_UV;
+
+layout (set=0, binding=0) uniform texture2D u_Tex;
+layout (set=0, binding=0) uniform sampler u_Sampler;
+
+layout (location = 0) out vec4 out_Color;
+
+void main() {
+    vec4 color = texture(sampler2D(u_Tex, u_Sampler), in_UV);
+    out_Color = color;
+}