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/__init__.py

@@ -19,6 +19,7 @@ from app.notify_client.job_api_client import JobApiClient
 from app.notify_client.status_api_client import StatusApiClient
 from app.its_dangerous_session import ItsdangerousSessionInterface
 from app.asset_fingerprinter import AssetFingerprinter
+from app.utils import validate_phone_number, InvalidPhoneError
 import app.proxy_fix
 from config import configs
 from utils import logging
@@ -65,6 +66,7 @@ def create_app(config_name, config_overrides=None):
     application.add_template_filter(nl2br)
     application.add_template_filter(format_datetime)
     application.add_template_filter(syntax_highlight_json)
+    application.add_template_filter(valid_phone_number)
 
     application.after_request(useful_headers_after_request)
     register_errorhandlers(application)
@@ -139,6 +141,14 @@ def format_datetime(date):
     return native.strftime('%A %d %B %Y at %H:%M')
 
 
+def valid_phone_number(phone_number):
+    try:
+        validate_phone_number(phone_number)
+        return True
+    except InvalidPhoneError:
+        return False
+
+
 # https://www.owasp.org/index.php/List_of_useful_HTTP_headers
 def useful_headers_after_request(response):
     response.headers.add('X-Frame-Options', 'deny')