Remove requirement for private properties to be prefaced with underscore

[thriggs]

Zend.NamingConventions.ValidVariableName rule requires an underscore for private class properties.

Actual Behavior

FILE: controller/DealerDetail.php
----------------------------------------------------------------------
FOUND 1 ERROR AFFECTING 1 LINE
----------------------------------------------------------------------
 35 | ERROR | Private member variable "newPrivateVar" must contain a
    |       | leading underscore
----------------------------------------------------------------------

This contradicts PSR-2:
https://www.php-fig.org/psr/psr-2/#42-properties

Property names SHOULD NOT be prefixed with a single underscore to indicate protected or private visibility.

We should be able to do something like this to exclude that rule:

<rule ref="Zend.NamingConventions.ValidVariableName.PrivateNoUnderscore">
    <exclude-pattern>*</exclude-pattern>
</rule>

[jasonmccallister]

I personally love this! I have not done this since PHP 5.2.

[hotline-emu]

This is a very legacy rule that I am more than glad to remove.

[jncarver]

I agree with this change - I really don't like leading underscores.