Toasts: Change showing timings and classes to keep toast `display:none` by default

Background:

Toast Component uses hide to force it get a display: none. This causes some strange attitude on initialized components that doesn't have show class, as ti overlaps page content cause of given opacity. We have also the hide class to use in order to keep the component hidden.

Solution:

We can borrow the Collapse component functionality, and by changing some class timings, we can avoid hide

Fixes #28752 (closed)

Preview: https://deploy-preview-33610--twbs-bootstrap.netlify.app/docs/5.0/components/toasts/