[Scenario] Introduce Activity Type object

Introduces Activity Type component to meet needs of #97

* Adds Activity Type as new component type. This contains power and comms costs (only)
* Modify Activity to read costs from child Activity Types. (Activity already reads child costs, but needed to truncate the start/end times of costs exposed via Activity Type)
* Add Mission Activity Types and User Activity Types as top-level components, serving as repositories for these types
* Adjust containment rules to support Activity Type objects and their repositories
* Add additional section to custom Info View UI for Activity components which includes Activity Types (interface is essentially similar to that used for Tags)
* Remove outdated "Activity Type" plain-text field from Activity, as well as power/comms fields. (These should reappear where power/comms have been set for prior models)