[web] Introduce a modal that allows adding new friends / blocking users

Summary:
The modal uses search modal internally and can be configured by setting name, labels and action (friend / block).

Depends on D4310

Test Plan:
Render the modal with some props and check if it looks correctly - it should match friend / block list modal.
Check if users are filtered according to excludedStatuses and if clicking the confirm button updates their status.

Reviewers: def-au1t, atul

Reviewed By: atul

Subscribers: ashoat, Adrian, yayabosh

Differential Revision: https://phab.comm.dev/D4311