Move some Rails app services to UserManager namespace

app/services/user_manager/create_invitations.rb

@@ -0,0 +1,19 @@
+module UserManager
+  class CreateInvitations < UserManagerService
+    def initialize(user:, amount:, notify: true)
+      @user = user
+      @amount = amount
+      @notify = notify
+    end
+
+    def call
+      @amount.times do
+        Invitation.create(user: @user)
+      end
+
+      if @notify
+        NotificationMailer.with(user: @user).new_invitations_available.deliver_later
+      end
+    end
+  end
+end