Fix case sensitive emails (#5485)

app/controllers/api/v1/admin/invitations_controller.rb

app/controllers/api/v1/migrations/external_controller.rb

app/controllers/api/v1/reset_password_controller.rb

app/controllers/api/v1/sessions_controller.rb

app/controllers/api/v1/users_controller.rb

app/controllers/external_controller.rb

app/services/recordings_sync.rb

db/data/20231030185844_lowercase_emails.rb

db/data_schema.rb

db/schema.rb