* Add variable for dropdown-divider-margin-y

For us to reassign the nav-divider-margin-y variable here, we have to rearrange some of the variables.

Fixes #26660.

* bump bundlesize

Fixes #26465

Fixes #27595

* Tweak the accessibility/reduced motion text

include mention of carousel slides, remove the (now inaccurate, as Firefox 63 includes it too) mention that support is limited to Safari/macOS

xref https://github.com/twbs/bootstrap/issues/27525

* Add new callout for reduced motion

* Add variable to control prefers-reduced-motion media query support

* Add callout about prefers-reduced-motion to all components currently using animation which are affected

This change follows exactly what was done for the `$grays`, `$colors`, and `$theme-colors` lists in #23260. This allows for easy addition of new breakpoints or grid containers also.

Define new variable for card header color

In case we set `$body-bg` to a dark color, we have to keep table contrast relevant.