gpu: move TextureUsage -> Texture.Usage

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

gpu/src/Texture.zig

@@ -30,6 +30,16 @@ pub inline fn destroy(texture: Texture) void {
     texture.vtable.destroy(texture.ptr);
 }
 
+pub const Usage = enum(u32) {
+    none = 0x00000000,
+    copy_src = 0x00000001,
+    copy_dst = 0x00000002,
+    texture_binding = 0x00000004,
+    storage_binding = 0x00000008,
+    render_attachment = 0x00000010,
+    present = 0x00000020,
+};
+
 test "syntax" {
     _ = VTable;
     _ = reference;