GDScript: Properly return value with await on non-coroutine

If the keyword `await` is used without a coroutine, it should still
return the value synchronally.

modules/gdscript/tests/scripts/runtime/features/await_without_coroutine.gd

@@ -0,0 +1,8 @@
+# https://github.com/godotengine/godot/issues/50894
+
+func test():
+	print(await not_coroutine())
+
+
+func not_coroutine():
+	return "awaited"

modules/gdscript/tests/scripts/runtime/features/await_without_coroutine.out

@@ -0,0 +1,6 @@
+GDTEST_OK
+>> WARNING
+>> Line: 4
+>> REDUNDANT_AWAIT
+>> "await" keyword not needed in this case, because the expression isn't a coroutine nor a signal.
+awaited