emails: move edit email flow to emails controller.

app/logical/user_email_change.rb

@@ -1,17 +0,0 @@
-class UserEmailChange
-  attr_reader :user, :password, :new_email
-
-  def initialize(user, new_email, password)
-    @user = user
-    @new_email = new_email
-    @password = password
-  end
-
-  def process
-    if User.authenticate(user.name, password)
-      user.update(email_address_attributes: { address: new_email })
-    else
-      user.errors[:base] << "Password was incorrect"
-    end
-  end
-end