Added phpcs configuration file and fixed coding standards issues

Author: krystalcode

.phpcs.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0"?>
+<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="krystalcode/api-iterator" xsi:noNamespaceSchemaLocation="phpcs.xsd">
+    <description>The coding standard for the API iterator library.</description>
+
+    <file>src</file>
+
+    <!-- Include the PSR standards -->
+    <rule ref="PSR1"></rule>
+    <rule ref="PSR2"></rule>
+    <rule ref="PSR12"></rule>
+
+</ruleset>

src/ClientInterface.php

@@ -49,5 +49,4 @@ interface ClientInterface
      *   paging.
      */
     public function list(array $options = [], array $query = []);
-
 }

src/Iterator.php

@@ -172,8 +172,8 @@ public function current(): \CachingIterator
             $this->query
         );
 
-        if ($count === FALSE) {
-          $this->count = count($this->pages);
+        if ($count === false) {
+            $this->count = count($this->pages);
         }
 
         $this->pages[$this->position]->rewind();
@@ -230,7 +230,7 @@ public function valid(): bool
 
         // We don't always know the total number of pages.
         // See the comments in the `count` method.
-        if ($this->count !== NULL && $this->position > $this->count) {
+        if ($this->count !== null && $this->position > $this->count) {
             return false;
         }
 
@@ -335,7 +335,8 @@ public function getAllItems()
      * @throws \InvalidArgumentException
      *   When the delay is set but in an incorrect format.
      */
-    protected function validateDelay() {
+    protected function validateDelay()
+    {
         if (!isset($this->delay)) {
             return;
         }