[lib] action for calling fetch all communities with names endpoint

Summary:
we'll dispatch this action to call fetch_all_communities_with_names on the authoritative keyserver

Depends on D13398

Test Plan:
dispatched action using useLegacyAshoatKeyserverCall. see gist: https://gist.github.com/vdhanan/df461cabc7a954ab1bc169104b98fbbb

saw success in redux and the correct payload

Reviewers: ashoat, tomek

Reviewed By: ashoat

Differential Revision: https://phab.comm.dev/D13399