High-degree easing functions shouldn't be jerky

## Bevy version

https://github.com/bevyengine/bevy/blob/72f096c91ea1056c41f2da821d310765c4482c00/crates/bevy_math/src/curve/easing.rs#L283-L295

## What you did

Low-degree easing functions have no choice to be jerky -- a quadratic one is [forced](https://www.desmos.com/calculator/oe93v9okni) to be jerky because it doesn't have enough degrees of freedom *not* to be.

If I'm using `QuinticInOut`, though, I'd expect it to be using those extra degrees to give continuous acceleration.

The current definition is still jerky, though: it jumps from +40 acceleration to -40 acceleration instantly:

Or if the existing ones shouldn't be edited, for some reason, should maybe some [Hermite](https://en.wikipedia.org/wiki/Hermite_interpolation#Statement_of_the_problem) in-out easing functions be added with 0 nth derivates at the endpoints?

Start in crates/bevy_math/src/curve/easing.rs at lines 283-295 and inspect the high-degree easing definitions. Compare the current QuinticInOut behavior with the linked acceleration example, then determine whether existing functions should change or Hermite in-out functions should be added. Done means the selected high-degree easing behavior has continuous acceleration through the transition.

Written by the indexing model from the issue text.