Replace all app references to support@hypothes.is with link to the support web form

We are moving to direct support requests more and more to use our support web form at https://web.hypothes.is/get-help/ Doing this helps improve the quality of the requests by prompting for details that make the support process more efficient.

To this end, we'd like to replace instances in the app that prompt or suggest the user email support@hypothes.is with prompts or suggestions to use the web form. These are almost exclusively in our error messages, but there may be other locations as well.

Search the app for references to support@hypothes.is, starting with the error messages mentioned in the issue, and review any other locations that prompt users to email support. Replace those prompts with the support web form link, then verify that no app references to the email address remain.

Written by the indexing model from the issue text.