Add dedicated messages for Onslaught control points without name

Fixes #2265 (closed). Replaces and closes !721 (closed).

This MR does what I suggested in the first post of #2265 (closed). There are separate messages for when an Onslaught control point has no name, written in such a way that they can be properly translated.

Please review and test. I don't really have a clue how the code works, so please bear with me. :)

I tested it myself and I found no bugs.

How to test:

• Play on a map w/o control point names like Courtfun
• Capture a control point
• Destroy a control point

Look inside the console and in the centerprint message after each event.

Now repeat on a map w/ control point names like Running Man CTF to verify the other messages still work.