Benjamin Franzke authored Dec 19, 2020 and Benni Mack committed Dec 21, 2020

Bootstrap v5 – introduced in #92616 – was added with CCS from beta1 but
JavaScript from alpha2. bootstrap.bundle.js was manually wrapped
into a AMD closure, and because bootstrap 5.0.0-beta1 contains alot of
changes regarding data tags, it couldn't be updated in the initial
patch.

Bootstrap is now bundled using rollup using the ES6 sources in order
to allow for automatic updates through `grunt build`.

popperjs – previously bundled into bootstrap distributed files –
is now added as dependency. The bootstap ES6 sources, that we now use
through rollup, do not bundle this external dependency (for good reasons).

Dependency added with:

   yarn add @popperjs/core

Further adaptions contained in this change to ensure beta1 compatibility:

a) Carousel "item" to "carousel-item" class migration
b) $.fn.modal(options) does no longer imply $.fn.modal('show')
c) Fix panels, both JS and CSS (card-group can't be used here)
d) All bootstrap data- tags are migra...