[native] implement keyserver list ui

Summary:
This diff introduces the UI for the keyserver selection list. For context here is a screenshot of the designs (please note, that elements like the connection indicator will be introduced in subsquent diffs)

Linear task: https://linear.app/comm/issue/ENG-4913/update-keyserver-list-ui

Depends on D9641

Test Plan:
Please see the screenshots below (the second keyserver is just a test "dummy" keyserver I added to the keyserver store when testing the add keyserver flow)

Reviewers: rohan, michal, inka

Reviewed By: rohan

Subscribers: ashoat, tomek, wyilio

Differential Revision: https://phab.comm.dev/D9642