* [PS-515] Use virtual scroll to speed up long user lists
WIP: this is currently showing a large blank area under the last user. Need to figure out why virtual-scroll-spacer is sized too large.
* Fix cdk-virtual-scroll styling
* Format csp for readability
* Set Viewport height
The viewport height was
* Calculate viewport height from item size
Virtual scroll viewports need set heights, we can emulate the old modal behavior by calculating an approximate height required by the viewport to display all items. It will not go beyond the window due to the `.modal-dialog-scrollable` class
* Remove modal css changes
* pr review
