EmailActorConfigurationModel should be CultureSpecific, and Actor must respect localized model value

Description

By default, the configuration model of Actor (in general) is not localized. It brings the same behavior to Forms across all languages.

In the case of an email actor, localizing the email template makes more sense. We have a request from a partner that the SendEmailAfterSubmissionActor property of FormContainer be CultureSpecific, so the email template (with localized text) is sent in a related language.

Though we discourage developers from modifying the property SendEmailAfterSubmissionActor to CultureSpecific, if a developer modifies it, the EmailActor should respect localized placeholder.

• use current language to generate the #placeholderName#
• use correct actual value (of submission, in the current language) to replace #placeholderName#

Note: Built-in #summary# placeholder works correctly as expected.