Validate CSVs fully

This commit extends the existing function to validate each row’s phone number
to also validate that all the required data is present.

It does this using the checking that the `Template` class can do when given
a template and a `dict` of values.

app/main/dao/services_dao.py

@@ -1,6 +1,6 @@
 from flask import url_for
 from app import notifications_api_client
-from app.main.utils import BrowsableItem
+from app.utils import BrowsableItem
 
 
 def insert_new_service(service_name, user_id):

app/main/dao/templates_dao.py

@@ -1,6 +1,6 @@
 from flask import url_for, abort
 from app import notifications_api_client
-from app.main.utils import BrowsableItem
+from app.utils import BrowsableItem
 
 
 def insert_service_template(name, type_, content, service_id):