NOTE: Disregard this PR, it was an early draft.

This is a draft

This work is part of Epic NCN-434, whose PRs should all be deployed together:

1693, NCN-633 plgUserHubzero (on user login, ensure user has a secret in the DB)
1683 NCN-439 com_members (manage user secret)
1676 NCN-437 com_newsletter (manage campaign secret)
1675 NCN-438 com_config (manage hub secret)
1695 NCN-702, NCN-440: com_newsletter (update verification, after porting functionality from custom com_reply)

Summary

This PR ports custom code from Nanohub (com_reply) into the core CMS component, com_newsletter.

It then updates access validation for one-click links to use the secrets (hub, user, and campaign) created in the Epic mentioned above, NCN-434.

[] Make sure there are links in the PR to the source JIRA card(s) and hubzero ticket(s)
[] Include a brief summary of the issue in your own words
[] Include a brief summary of the fix/changed code
[] Include a brief summary of your testing. What did you specifically do to investigate that this change has the correct results?
[] Indicate if the change needs to be hotfixed to any production hubs before a normal core rollout
[] Double check someone is assigned to review the ticket

Thanks!