[lib] Handle farcaster_mutual case in robotext/notificationTexts

Summary:
Show different message in robotext/notificationTexts when operation is of type farcaster_mutual.

Based on https://github.com/CommE2E/comm/commit/7d43cd1575df7b6f0a23d0e5dd88d63bbfab7bf8

(adding @ashoat as blocking to get sign off on copy)

Depends on D11457

Test Plan:
Appears as expected:

Reviewers: ashoat, ginsu, varun, tomek, will

Reviewed By: ashoat

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11458