Loading dependency (Lingo) from within SemanticGlossary

[mwjames]

I created [0] to seek advice on how to load a required extension as I'm unhappy about the "// must NOT use ExtensionRegistry::getInstance() to avoid recursion!" which may create some unanticipated issues sooner or later.

[0] https://phabricator.wikimedia.org/T152263

[kghbln]

There is a patch effort by a third party programmer starting to rot.