Don't register disabled telesopes

[symmsaur]

If a telescope is configured as disabled don't even create the TelescopeContainer for it.

This lessens confusion about which telesopes are actually enabled.

[symmsaur]

I had some issues when before figuring out that telescopes can be disabled. It would print "Creating telescope foo" even when foo was disabled. To help with understanding and creating a smaller state space this changes so that disabled telescopes are ignored before being created.