[Scenario] Allow user to specify types & tags from Activity wizard

Per nasa/MCT-Plugins#133, allow the user to specify initial Activity Type and Tag associations for an Activity from the Activity Create wizard. Differs from issue insofar as user interface for applying these tags is a dialog triggered by a "+" button; this exhibits closer parity to user interface from nasa/MCT-Plugins#129 and nasa/MCT-Plugins#130, particularly with regard to allowing the user to select multiple such associations.

Additionally, refactors tagging dialog slightly such that it is reusable from this context.