feat(utils): added misc functions file with utilities

Added useful misc utilities that don't belong in a specific class/domain and should be available globally.

composer.json

@@ -9,6 +9,9 @@
     "php-di/slim-bridge": "^3.4"
   },
     "autoload": {
+      "files": [
+        "src/Utils/Functions.php"
+      ],
       "psr-4": {
         "Models\\": "src/Models/",
         "Interfaces\\": "src/Interfaces",

src/Utils/Functions.php

@@ -0,0 +1,25 @@
+<?php
+
+/**
+ * Converts camelCase to snake_case.
+ *
+ * @see https://gist.github.com/carousel/1aacbea013d230768b3dec1a14ce5751
+ * @param $input
+ * @return string
+ */
+function camel_to_snake($input)
+{
+    return strtolower(preg_replace('/(?<!^)[A-Z]/', '_$0', $input));
+}
+
+/**
+ * Converts snake_case to camelCase.
+ *
+ * @see https://gist.github.com/carousel/1aacbea013d230768b3dec1a14ce5751
+ * @param $input
+ * @return string
+ */
+function snakeToCamel($input)
+{
+    return lcfirst(str_replace(' ', '', ucwords(str_replace('_', ' ', $input))));
+}