Add file and dir temporary utilities

Co-authored by @Alex2782 for the Android bindings.
Many thanks to the reviewers also.

Co-authored-by: Alex <alex.hart.278@gmail.com>

core/os/os.cpp

@@ -276,6 +276,10 @@ String OS::get_cache_path() const {
 	return ".";
 }
 
+String OS::get_temp_path() const {
+	return ".";
+}
+
 // Path to macOS .app bundle resources
 String OS::get_bundle_resource_dir() const {
 	return ".";