Add RT format test.

test/decode-format.slang

@@ -0,0 +1,28 @@
+#version 450
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+   mat4 MVP;
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 1) uniform usampler2D Source;
+
+void main()
+{
+   vec4 current = unpackUnorm4x8(texture(Source, vTexCoord).r);
+   FragColor = current;
+}

test/format.slang

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+#version 450
+
+#pragma format R32_UINT
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+   mat4 MVP;
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 0) out uint FragColor;
+layout(set = 0, binding = 1) uniform sampler2D Source;
+
+void main()
+{
+   vec3 current = texture(Source, vTexCoord).rgb;
+   FragColor = packUnorm4x8(0.3 * vec4(current, 1.0));
+}

test/format.slangp

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+shaders = 2
+shader0 = format.slang
+shader1 = decode-format.slang
+scale_type0 = source
+scale0 = 1.0
+filter_linear0 = false
+filter_linear1 = false