[web] introduce keyserver selection list

Summary:
This diff introduces the barebones KeyserverSelectionList. Subsequent diffs will handle introducing the add and remove keyserver user experiences

Linear task: https://linear.app/comm/issue/ENG-5494/implement-remaining-elements-of-the-keyserver-selection-screen-ui

Depends on D9891

Test Plan:
Please see the screenshot below

Reviewers: inka, rohan, michal

Reviewed By: inka

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D9892