Add Tablet/Trackpad 3D navigation preset

[RobProductions]

Following up on the discussion from #85331 , if a user enables "emulate 3 button mouse" with the Godot preset, they will see the camera always orbit because the Godot preset doesn't use any hotkey for orbit. Bringing in "Alt" as a fallback key for 3 button mouse users (which is what the code used to do) would eliminate their ability to customize the orbit button, so instead the idea of a Tablet/Trackpad preset seems to work much better.

With this change, 3 button mouse is now tied to the navigation preset, so if you set the preset to Tablet/Trackpad it will enable 3 button mouse and also set the orbit key to "Alt" so that Tablet users have better default settings. I also added options and functionality for mouse buttons 4 and 5; none of the presets use this but this should allow users to customize 3D nav further for specific tablet pens or mice.

With this, tablet and trackpad users can simply change the preset setting rather than changing "Emulate 3 button mouse" which should provide a clearer experience now that everything is customizable. Similarly, if someone changes "Emulate 3 button mouse" from the default the preset will change to Custom which should help clarify that they are going outside of the default options.

One question I had about the presets: is it okay to keep pushing down the Custom preset to a different number if we add more presets that go above it in the UI? I numbered them in this commit for clarity but say for example we add a Blender preset in the future, is it okay for that to become element 4 with Custom getting pushed to element 5? Or should I just reorder Custom to be at the top now for better futureproofing?

Thanks and let me know if there are any questions :)

[AThousandShips]

The new mode needs to be documented in the settings docs

[RobProductions]

Thanks for the help! I've updated the docs and changed Custom back to value 3 so that shouldn't be a compat issue anymore, let me know if that looks good

[Mickeon]

I don't think it's worth being so explicit over this one editor setting. The other affected ones are listed at the bottom of the description.

[RobProductions]

@Mickeon Done, thanks!

[Calinou]

Tested locally on a MacBook Pro, it works as expected. The shortcuts with this preset make sense to me.

[Repiteo]

Thanks!