Split off from T335925#11584556. Currently, there is close to 0 visibility into pixel failures, in that people need to open the tool and check manually. It would be nice to have a bot automatically report new failure to phabricator, so maintainers can address them promptly.

As an example of existing tool, see @phaultfinder and tasks like T412052. The pixel repo could store a YAML/JSON file that defines whether alerts are enabled for a given extension, and what tags to use on phabricator (ideally both a project and a people tag). Like phaultfinder, the bot should check whether a task for the failure already exists, and if so not do anything.