Notifications configuration

The upcoming notification feature should be configured by each data owner, with the help of provided templates. How this could be organized:

• a set of regex to apply to the processing logs as well as a count threshold to trigger a notification based on this regex. For example, a regex to catch points being filtered out and sending a notification if more than 10 points have been filtered out on a single parameter
• the user could chose the regex from a set of existing templates (provided by the platform as well as by the site admin) or add their own ones
• the possibility to define some kind of a grace period before a notification is sent again (there is no point in flooding the data owner mailbox with a given parameter having too many points filtered out every single time meteoio_timeseries runs again (for example, hourly) but sending the notification again 3 days later if nothing has been done would be a great reminder)
• the possibility to tag such events as "addressed": for example, tagging that the root cause of a given parameter triggering its filters too often has been addressed, but obviously past data will still trigger the filters but should not generate a notification anymore
• the possibility to tag a station as decommissioned, so there is no need to report that there is no new data coming in!