[native] implement UI for selecting a farcaster channel

Summary:
This diff introduces the action sheet "dropdown component" for selecting a farcaster channel that the user follows and wants to tag to their Comm community.

Please note that the UI for this screen is still a WIP and subsequent diffs will introduce the rest of the elements needed on this screen (ie the submit button)

Linear task: https://linear.app/comm/issue/ENG-7546/introduce-a-farcaster-dropdown-component + https://linear.app/comm/issue/ENG-7545/fetch-all-the-farcaster-channels-the-community-creatoradmin-is-active

Depends on D11682

Test Plan:
Please see the demo video below

Reviewers: atul, inka, ashoat

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11683