Ruleset: forbid use of the ! not operator

`0` is a valid token stack pointer, so in most cases a loosey comparison against `false` in conditions is dangerous in the context of code for PHPCS.

With that in mind, I propose forbidding it.

Author: jrfnl

PHPCSDev/ruleset.xml

@@ -151,6 +151,11 @@
     <!-- Only one object structure per file. -->
     <rule ref="Generic.Files.OneObjectStructurePerFile"/>
 
+    <!-- Disallow non-strict comparisons and the use of the not operator. -->
+    <rule ref="Squiz.Operators.ComparisonOperatorUsage">
+        <exclude name="Squiz.Operators.ComparisonOperatorUsage.ImplicitTrue"/>
+    </rule>
+
 
     <!--
     ####################################################################