This commit introduces scheduled problem checks for the admin dashboard, which are long running or otherwise cumbersome problem checks that will be run every 10 minutes rather than every time the dashboard is loaded. If these scheduled checks add a problem, the problem will remain until it is cleared or until the scheduled job runs again.
An example of a check that should be scheduled is validating credentials against an external provider.
This commit also introduces the concept of a `priority` to the problems generated by `AdminDashboardData` and the scheduled checks. This is `low` by default, and can be set to `high`, but this commit does not change any part of the UI with this information, only adds a CSS class.
I will be making a follow up PR to check group SMTP credentials.
We have a few places in the code where we need to validate various email related settings, and will have another soon with the improved group email settings UI. This PR introduces a class which can validate POP3, IMAP, and SMTP credentials and also provide a friendly error message for issues if they must be presented to an end user.
This PR does not change any existing code to use the new service. I have added a TODO to change POP3 validation and the email test rake task to use the new validator post-release.
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
