vulkan: Add pixel-formats to query format properties

We need a database of pixel format properties to remove hardcoded magic
numbers. This commit creates a simple function to query the bytes per
pixel for common RGBA formats.

This should be promoted to or superseeded by a common spa namespaced
version.

spa/plugins/vulkan/pixel-formats.h

@@ -0,0 +1,12 @@
+/* Spa */
+/* SPDX-FileCopyrightText: Copyright © 2023 columbarius */
+/* SPDX-License-Identifier: MIT */
+
+#include <stdint.h>
+#include <stdbool.h>
+
+struct pixel_format_info {
+	uint32_t bpp;	// bytes per pixel
+};
+
+bool get_pixel_format_info(uint32_t format, struct pixel_format_info *info);