As described in #3247, the pluggable alert condition forms introduced in 2.2 are propagating data using the wrong data types to the server, which is also failing to fix or properly validate that data, resulting in wrong objects being written into MongoDB.
To avoid this situation, this PR is doing the following:
Check if the configuration is valid against the requested configuration for that alert condition, ensuring all required fields are set, and the right data types are being used. If that is not the case, a `ConfigurationException` will be raised. Refs #3247
Having custom pluggable forms, and falling back to using `ConfigurationForm` when none was provided sounded like a great idea, but in the end it is tricky, as forms behaved in slightly different ways, and they also asume the developer would follow certain implied conventions. As this way also feels inconsistent from a user's point of view, I think it is best at this point to only use `ConfigurationForm` components for now, and think of a better way of doing custom forms for alert conditions in future versions.