Prepare for moving editor and classref translations to godot-editor-l10n repo
- Separate editor interface and property translations.
- Add property translation in TranslationServer.
- The split and merge of the POT/PO/Makefiles and extract scripts is done
directly in godot-editor-l10n, the files will be removed in the next commit.
- Remove the hardcoded "to_include" lists from the SCsub, we'll only commit the
files which are ready to inclue.