Add a way to return to service page

[knguyenBC]

### User story As a user, I want a way to return back to the service page from vc-authn page, so that I can easily go back to the service page if I decide to not not continue sharing my information, I decide to decline the proof request, if the proof request was rejected or an error occurred.

Acceptance Criteria

• Add a "Return to service" button that takes people back to the service page

[loneil]

Question about capabilities: https://stackoverflow.developer.gov.bc.ca/questions/1240

and some discussion: https://chat.developer.gov.bc.ca/channel/sso?msg=nha9LiEGKbWxjrPHj