Add check name in results

[ernilambar]

In this PR:

• Every Check is assumed to have a name. So get_name() has been added to interface Check.
• check has been added to final class Check_Result.
• includes/Traits/Amend_Check_Result.php - Methods are updated to accomodate newly added check field.
• Late_Escaping_Check.php: get_name() method is implemented. Eg:

public function get_name() {
   return 'late_escaping';
}

Output:

[ernilambar]

Requesting for feedback whether this approach is good or not.

cc: @swissspidy @felixarntz @mukeshpanchal27

[felixarntz]

@ernilambar I like the idea of optionally supporting the inclusion of the check identifier. That said, I think we'll need to carefully think about how to implement that change. Preferably, this should be handled in a central place, without having to define the check identifiers as both array keys and in each class.

[ernilambar]

@felixarntz May be this approach is better. Please review it. #380