Allow users to mark/flag runs in test mode

[christad92]

Related to #2524 but different.

We should enable users to flag runs as test runs so that collaborators can tell when the runs were requested in "test mode" vs. which are real production.

In test mode, we don't need to send failure alerts because most of the runs are being debugged in real time by a collaborator.

On the history page, users should be able to filter the view to exclusively show runs in test mode or production mode.

When the project is ready to be deployed to live, users should switch the project to live mode, and runs executed in production mode should tagged as such.