[web] intorduce loading logic to relationship prompt button

Summary:
This diff updates the relationship prompt button in web to consume the loading logic from useRelationshipPrompt

Depends on D12593

Test Plan: Confirmed that the loading logic works as expected in the relationship prompt button for both the relationship prompt and user profiles

Reviewers: ashoat, inka

Reviewed By: ashoat

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12595