TestEmailBuilder should follow guidelines for writing an email builder

Problem/Motivation

See docs → .

Proposed resolution

1. In TestEmailBuilder should have a create parameter for 'to'. Then in TestEmailForm::submitForm() can call $this->emailFactory->sendTypedEmail().
2. TestEmailBuilder::fromArray() is unnecessary.

Remaining tasks

User interface changes

API changes

The create parameters could be considered an API - someone could have written their own code to send a test email. Therefore the $to parameter will be optional.

Data model changes