Ruleset: check code style against PSR12

This commit:
* Adds the complete PSR12 ruleset to this standard.
* Excludes one PSR12 sniff which requires a higher minimum PHP version (PHP 7.1), than the projects in the organisation support.
* Removes any individual sniff inclusions for sniffs also included in PSR12.
    This can be verified by running the following command which shows exactly which sniffs are included in PSR12:
    ```bash
    vendor/bin/phpcs --standard=PSR12 -e
    ```

Author: jrfnl

PHPParallelLint/ruleset.xml

@@ -3,7 +3,33 @@
 
     <description>A coding standard for projects in the PHP Parallel Lint organisation.</description>
 
-    <rule ref="Generic.Functions.FunctionCallArgumentSpacing"/>
+    <!--
+    #############################################################################
+    CHECK CODE STYLE AGAINST PSR12
+    https://www.php-fig.org/psr/psr-12/
+    #############################################################################
+    -->
+    <rule ref="PSR12">
+        <!-- Constant visibility is a PHP 7.1 feature and cannot (yet) be used. -->
+        <exclude name="PSR12.Properties.ConstantVisibility"/>
+    </rule>
+
+    <!-- ## Sniff specific configuration for sniffs included in PSR12 ## -->
+
+    <rule ref="Generic.Files.LineLength">
+        <properties>
+            <property name="lineLimit" value="125"/>
+            <property name="absoluteLineLimit" value="200"/>
+        </properties>
+    </rule>
+
+
+    <!--
+    #############################################################################
+    MISCELLANEOUS ADDITIONAL RULES
+    #############################################################################
+    -->
+
     <rule ref="PEAR.Functions.FunctionDeclaration"/>
     <rule ref="PEAR.Functions.FunctionCallSignature"/>
     <rule ref="PEAR.Functions.FunctionCallSignature.Indent">
@@ -15,35 +41,23 @@
     <rule ref="PEAR.Functions.FunctionCallSignature.ContentAfterOpenBracket">
         <severity>0</severity>
     </rule>
-    <rule ref="PEAR.Functions.ValidDefaultValue"/>
 
-    <rule ref="Generic.PHP.DisallowShortOpenTag"/>
-    <rule ref="Generic.PHP.LowerCaseConstant"/>
     <rule ref="Generic.PHP.NoSilencedErrors"/>
     <rule ref="Squiz.PHP.GlobalKeyword"/>
     <rule ref="Squiz.PHP.LowercasePHPFunctions"/>
     <rule ref="Squiz.PHP.NonExecutableCode"/>
 
     <rule ref="Generic.Strings.UnnecessaryStringConcat"/>
 
-    <rule ref="Generic.WhiteSpace.DisallowTabIndent"/>
     <rule ref="PEAR.WhiteSpace.ScopeClosingBrace"/>
 
     <rule ref="PEAR.Classes.ClassDeclaration"/>
 
-    <rule ref="Generic.ControlStructures.InlineControlStructure"/>
     <rule ref="PEAR.ControlStructures.ControlSignature"/>
 
-    <rule ref="Generic.Files.LineLength">
-        <properties>
-            <property name="lineLimit" value="125"/>
-            <property name="absoluteLineLimit" value="200"/>
-        </properties>
-    </rule>
     <rule ref="Zend.Files.ClosingTag"/>
 
     <rule ref="Generic.NamingConventions.ConstructorName"/>
-    <rule ref="Generic.NamingConventions.UpperCaseConstantName"/>
 
     <rule ref="Generic.Metrics.NestingLevel"/>
     <rule ref="Generic.Metrics.CyclomaticComplexity"/>