[keyserver] add comm config for authoritative facaster bot boolean variable

Summary:
Adds a farcaster bot config to facts which includes a boolean value for authoritativeFarcasterBot which decides whether or not we create a farcaster channel tagged community if not already existent or create a sidebar when a channel isn't specified.

Depends on D13774

Test Plan: Tested later in the stack by setting to true and ensured tagged communities were being created properly

Reviewers: ashoat, varun

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13781