Messaging Template Enhancements

1. Templates should be able to be assigned to multiple listings or multiple channels. This could be done via "exclude" or just multi-select; this functionality exists in other messaging areas on HA so it's strange it doesn't exist in templates.

Templates should be assignable via tags, channels, listings. 

2. Our communication team sends the wrong messages all the time, because the list of templates is too long and not filtered enough. They shouldn't even see the "no pets" option for pet friendly places, but with over 100 listings, we're not going to clone the template 30x for one type, and 70x for the other. 

3. Our workaround is paying another software company to more effectively manage our communcations.