TemplateList gets a list of templates in a current folder separately,
so we need to make sure `service.get_templates` checks for the
appropriate user permission
Sometimes, when filtering the view by template type, the message was
saying the folder was empty, when really it should have been saying that
there were no templates of the ‘type’ you’re looking for, eg:
> There are no email templates in this folder
This was because it was looking at the filtered list of templates, not
all templates to determine whether a folder was really empty.
We already have a pattern for navigation folders and searching for
templates – let’s use it for the copy page too. And I reckon we can
represent services as folders if the user has multiple services they
could copy a template from.
Since you can now see them when searching you should also be able to
select and move them. Which means that they needed to be included in
the `Form`’s list of possible choices of things to move.
The Jinja template for the ‘choose templates’ page is now pulling in
data from a lot of diparate places in order to work out what to show. As
we add more logic about what to show (in order to make the live search
work) it’s going to get harder to have all this logic in the Jinja
template.
This commit refactors it back into Python where we have more language
features for managing complex logic.
It’s a bit weird to call this file a model, in that it’s dealing with
some presentational logic, rather than just data. Conceptually it’s more
like a view model[1].
1. https://en.wikipedia.org/wiki/Model%E2%80%93view%E2%80%93viewmodel
