Allow user to type in solar system body index when selecting local target

[jorisvddonk]

Noctis IV (NIV) allows users to type in a local solar system body index when selecting a local target. This allows easy navigation, and makes it possible to navigate to a planet or moon without trying to physically locate it.

For example, typing '4' allows selecting the 4th planet, P04 (indexed on 1) - Felysia in this case:

"1/3" allows selecting the first moon of planet P03. SESTRATRIFAL (designated P06) in this case.
"1/5" allows selecting the first moon of planet P05. RADHARPHIS (designated P22) in this case.

Note that:

• NIV does not allow you to type a '/' in twice.
• NIV does not display the target name and index dynamically whilst typing it. That is, only after you hit ENTER do you know which planet/moon you targeted, what its name is, and what its designation is.
• If you type in a planet id that does not exist, the FCS Status displays 'NOT EXTANT', which hides your input until you type a number, slash or backspace again, at which point the input is shown again. This allows you to correct your mistake immediately.
• Moons can NOT be targeted by typing their designator. Whilst RADHARPHIS is designated P22, typing '22' results in "NOT EXTANT". Whilst I think it may be wise to replicate this behaviour, perhaps it'd be nice to allow users to type in "P22" and "P06" as a nice accessibility feature to directly target a planet or moon without knowing its exact solar system topology.
• NIV displays some odd behaviour if you enter large numbers that exceed the local solar system's number of bodies; in certain cases it can even crash. Obviously, this shouldn't be replicated.