Add Calendly invite link to survey response page [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

It adds a link on the Survey Response page when the invite_link URL parameter is present, we are on gitlab.com and the calendly_invite_link feature flag is enabled.

Part of issue: gitlab-org/growth/engineering#5437 (closed)

Design: gitlab-org/growth/product#1678 (closed)

Feature flag rollout issue: #330340 (closed)

To test this out, run Feature.enable(:calendly_invite_link) in the console and visit http://localhost:3000/-/survey_responses?invite_link=true.

Screenshot