Have permissions decorators check user signed in

Rather than force us to write the decorators in a specific order let’s
just have one decorator call the other. This should make fewer lines of
code, and fewer annoying test failures. It also means that the same way
of raising a `401` (through the `current_app` method) is used
everywhere.

app/main/views/inbound_number.py

@@ -1,5 +1,4 @@
 from flask import render_template
-from flask_login import login_required
 
 from app import inbound_number_client
 from app.main import main
@@ -7,7 +6,6 @@ from app.utils import user_is_platform_admin
 
 
 @main.route('/inbound-sms-admin', methods=['GET', 'POST'])
-@login_required
 @user_is_platform_admin
 def inbound_sms_admin():
     data = inbound_number_client.get_all_inbound_sms_number_service()