Rework decluttering

[eggrobin]

There was a long discussion on Discord with @ezsnackeur, @AntonKuzin, and @Nazfib, best summarized by @Nazfib:
https://discord.com/channels/319857228905447436/480397772248580098/1324359431860785153

I do think it is silly that you can disable the equipotential lines in the Lagrange frames, since that's literally the most important feature of that frame; it definitely should not be disabled by default, or persistently.

As for seeing other planets' orbits in frames where they are not really relevant (e.g. the Moon's orbit in a JCI frame, or Venus' orbit in ECEF, I can see the argument for having the declutter persistent for those. I would not declutter by default though; seeing all the planets move around the Earth in ECEF the first time you open the map view is a great reminder to new players that everything is plotted in a reference frame, which the player must select and switch to show what they want to see.

The idea of the declutter « panic » button, inspired by the Mirage 2000C HUD, does not seem to actually work. There is no need for a way to hide equipotentials, they are relevant whenever the Lagrange frame is relevant. It makes sense to persist hiding irrelevant lines. This could perhaps benefit from being a per-frame setting, e.g., hide all celestials in ECEF but not in ECI.