Move alert validator to python API

[wk9874]

Alert validator model is currently duplicated across both Integrations and Optimisations. Should move it to Python API so that both can use it from single location.

Also need to update the model for 'user' alerts, but I dont understand what those are so need to ask Kristian about those.

[wk9874]

No longer required with v2 of the API, since create_alert has been split out into different methods depending on the type.

These can be defined and created up front by associating them with a disabled run if required