[web] introduce keyserver selection list item

Summary:
introduce KeyserverSelectionListItem component. This component will be used in the keyserver selection list.

For context here are the figma designs:

Linear task: https://linear.app/comm/issue/ENG-5493/introduce-keyserver-list-item-ui

Depends on D9905

Test Plan:
Please see screenshots below (please note the blue add button is temporary and is not part of this diff)

Reviewers: inka, rohan, michal

Reviewed By: inka

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9891