Add adjustable delay to how fast QuickDrop fires

[clyfordv]

Saw enough talk both ways that I'd figured I'd bang this out as an option. Adds a minimum time for QuickDrop to fire.

Reasons:

• Provides a balance knob
• Current drop looks a little too sharp (units fly off at an odd velocity, transport isn't settled)

[clyfordv]

The original motive was not even to make transports drop faster, but to untangle drop time from transport LiftFactor and K factors, given that:

1. Transports are pretty particular about how close they need to be to their drop point before releasing cargo.
2. Adjusting flight characteristics so that transports don't (as an example) descend from mountains at a glacially slow pace caused them to oscillate around their drop point, taking even longer.

If [1] has been fixed (through an engine patch?) I could see quick drop no longer being necessary, but as long as it remains [2] is going to apply.

I didn't see a huge need for the addition of this delay, but it was raised as an issue on the discord (not a majority opinion, perhaps) so I figured I'd bang it out.

(And a minor point, but the visuals of the transports taking a moment to level out are much better, which means we could undo the bank factor changes that came with the original QuickDrop because dropping at a steep bank looked rather jarring.)

[lL1l1]

When I was logging the tick timings I noticed that it drops without having to abort navigation when arriving to the drop location from a lower surface height (e.g. from water/land onto a cliff/plateau), and it does abort navigation when arriving to the drop location from an equal surface height. So while it isn't a perfect balance knob because it doesn't handle cliff drops, it can be useful to make normal drops faster or slower.

[Garanas]

With these changes

https://github.com/FAForever/fa/assets/15778155/664a83d7-a23f-4123-92af-452d399d1caf

Without the quick drop feature

https://github.com/FAForever/fa/assets/15778155/96d337da-0484-4ac9-bab4-5768b05a2b86

There's not much difference in my opinion. Of course some maps have rather extreme cliffs, but there's a limit to what we can (not) support.