Improve activity import to support updates

As I've delved through this code I don't think it makes sense for the checkbox about matching options to be used on the activity form. The reason for it on the contact form is the multiple possible options. For activity it is either an id match, if present, or nothing

I think ideally this would be dependent on activity id being mapped on the specified row - ie it could be possible to have a combination of with & without.

@DaveD tracking gl for this