video_core: Implement vulkan clear specified channel

src/video_core/host_shaders/CMakeLists.txt

@@ -45,6 +45,8 @@ set(SHADER_FILES
     smaa_neighborhood_blending.vert
     smaa_neighborhood_blending.frag
     vulkan_blit_depth_stencil.frag
+    vulkan_color_clear.frag
+    vulkan_color_clear.vert
     vulkan_fidelityfx_fsr_easu_fp16.comp
     vulkan_fidelityfx_fsr_easu_fp32.comp
     vulkan_fidelityfx_fsr_rcas_fp16.comp

src/video_core/host_shaders/vulkan_color_clear.frag

@@ -0,0 +1,14 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#version 460 core
+
+layout (push_constant) uniform PushConstants {
+    vec4 clear_color;
+};
+
+layout(location = 0) out vec4 color;
+
+void main() {
+    color = clear_color;
+}

src/video_core/host_shaders/vulkan_color_clear.vert

@@ -0,0 +1,10 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#version 460 core
+
+void main() {
+    float x = float((gl_VertexIndex & 1) << 2);
+    float y = float((gl_VertexIndex & 2) << 1);
+    gl_Position = vec4(x - 1.0, y - 1.0, 0.0, 1.0);
+}