Add code sniffer configuration

Author: DEVizzent

phpcs.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="vendor/squizlabs/php_codesniffer/phpcs.xsd">
+
+    <arg name="basepath" value="."/>
+    <arg name="cache" value=".phpcs-cache"/>
+    <arg name="colors"/>
+    <arg name="extensions" value="php"/>
+
+    <rule ref="PSR12">
+        <exclude name="PSR2.Methods.MethodDeclaration.Underscore"/>
+    </rule>
+
+    <rule ref="Generic.Files.LineLength">
+        <properties>
+            <property name="lineLimit" value="150"/>
+            <property name="absoluteLineLimit" value="0"/>
+        </properties>
+    </rule>
+
+    <file>src</file>
+    <file>tests</file>
+
+</ruleset>