Change get_providers endpoint to return no of SMS sent by each provider

In addition to the existing provider data, we also want return the number of
billable units (muliplied by the rate multiplier) that each SMS provider sent
this month. This will be used on the platform admin providers page.

Since we can no longer get all the information we need from the provider details
schema, this makes a new DAO function to get all the data for the endpoint.

app/provider_details/rest.py

@@ -2,9 +2,9 @@ from flask import Blueprint, jsonify, request
 
 from app.schemas import provider_details_schema, provider_details_history_schema
 from app.dao.provider_details_dao import (
-    get_provider_details,
     get_provider_details_by_id,
     dao_update_provider_details,
+    dao_get_provider_stats,
     dao_get_provider_versions
 )
 from app.dao.users_dao import get_user_by_id
@@ -19,8 +19,23 @@ register_errors(provider_details)
 
 @provider_details.route('', methods=['GET'])
 def get_providers():
-    data = provider_details_schema.dump(get_provider_details(), many=True).data
-    return jsonify(provider_details=data)
+    data = dao_get_provider_stats()
+
+    provider_details = [
+        {'id': row.id,
+         'display_name': row.display_name,
+         'identifier': row.identifier,
+         'priority': row.priority,
+         'notification_type': row.notification_type,
+         'active': row.active,
+         'updated_at': row.updated_at,
+         'supports_international': row.supports_international,
+         'created_by_name': row.created_by_name,
+         'current_month_billable_sms': row.current_month_billable_sms}
+        for row in data
+    ]
+
+    return jsonify(provider_details=provider_details)
 
 
 @provider_details.route('/<uuid:provider_details_id>', methods=['GET'])