[keyserver] update joinThread to automatically make farcaster channel lead a community admin
Summary:
depends on D13295
updated the joinThread logic to:
- fetch user's farcaster ID from identity service
- fetch farcaster channels led by fid
- if channel tag for community is in list of channels led by fid, make user admin of thread
Test Plan:
- created two new communities and tagged them with /varun (my new channel, of which i'm the lead) and /sovereignty (i just follow this channel)
- registered a new user and linked my farcaster account
- confirmed that i was admin of the community tagged with /varun and a member of the community tagged with /sovereignty
Reviewers: ashoat
Reviewed By: ashoat
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D13300