general: Rename NewUUID to UUID, and remove the previous UUID impl

This completes the removal of the old UUID implementation.

src/input_common/drivers/gc_adapter.cpp

@@ -248,7 +248,7 @@ bool GCAdapter::Setup() {
         std::size_t port = 0;
         for (GCController& pad : pads) {
             pad.identifier = {
-                .guid = Common::NewUUID{},
+                .guid = Common::UUID{},
                 .port = port++,
                 .pad = 0,
             };