SetFromTest: reorganize success tests to use data providers
SetFromTest: reorganize success tests to use data providers

* Merges the two "success" tests from the `testAddressing()` and the `testAddressing2()` methods into one `testSetFromSuccess()` method.
* Adds additional assertions to more comprehensively verify that the method did what was expected, i.e. set the `From`, `FromName` and `Sender` properties.
* Maintains the same test cases.
* Makes it easier to add additional test cases in the future.

PHPMailer/PHPMailer,jimjag/PHPMailer,PHPMailer/PHPMailer,nawawi/PHPMailer,nawawi/PHPMailer,jimjag/PHPMailer