Is this a new component or an extension of an existing one?
Modal/Backdrop

Describe the feature
This would be work necessary as part of patternfly/patternfly-react#12552. This React PR adds styles for testing purposes, so once the animations and styles there are signed off by designers and CSS devs, we can port those styles into here to live.

Are there visuals for this feature? If applicable, please include examples for each state and for varying widths
Include screenshots or links to Marvel or other mockups.

Any other information?

Jira Issue: PF-4466