Move redirect_to_signin helper to new util module

We'll expand this module in later commits.

app/main/views/code_not_received.py

@@ -4,7 +4,7 @@ from app import user_api_client
 from app.main import main
 from app.main.forms import TextNotReceivedForm
 from app.models.user import User
-from app.utils import redirect_to_sign_in
+from app.utils.login import redirect_to_sign_in
 
 
 @main.route('/resend-email-verification')

app/main/views/two_factor.py

@@ -16,7 +16,8 @@ from app import user_api_client
 from app.main import main
 from app.main.forms import TwoFactorForm
 from app.models.user import User
-from app.utils import is_less_than_days_ago, redirect_to_sign_in
+from app.utils import is_less_than_days_ago
+from app.utils.login import redirect_to_sign_in
 
 
 @main.route('/two-factor-email-sent', methods=['GET'])

app/main/views/verify.py

@@ -17,7 +17,7 @@ from app.main import main
 from app.main.forms import TwoFactorForm
 from app.models.service import Service
 from app.models.user import InvitedOrgUser, InvitedUser, User
-from app.utils import redirect_to_sign_in
+from app.utils.login import redirect_to_sign_in
 
 
 @main.route('/verify', methods=['GET', 'POST'])

app/main/views/webauthn_credentials.py

@@ -10,7 +10,8 @@ from app.main.views.two_factor import log_in_user
 from app.models.user import User
 from app.models.webauthn_credential import RegistrationError, WebAuthnCredential
 from app.notify_client.user_api_client import user_api_client
-from app.utils import is_less_than_days_ago, redirect_to_sign_in
+from app.utils import is_less_than_days_ago
+from app.utils.login import redirect_to_sign_in
 from app.utils.user import user_is_platform_admin