Updated PHP version for PHP7.2+

Removed PHP5 (no longer supported)
Renamed PHP7 to PHP - consistent with other kata
Added the same helpers as other PHP Kata
Updated the code to PHP7.2+ standard
Didn't change GildedRose updateQuality method
Updated GildedRoseTest (still failing)
Added ApprovalTest (passing)
- same text file as texttests / ThirtyDays / stdout.gr (only renamed).

php/phpstan.neon

@@ -0,0 +1,16 @@
+includes:
+    - vendor/symplify/phpstan-extensions/config/config.neon
+    - vendor/phpstan/phpstan-phpunit/extension.neon
+
+parameters:
+    paths:
+        - src
+        - tests
+        - fixtures
+
+    # The level 8 is the highest level
+    level: 8
+
+    checkGenericClassInNonGenericObjectType: false
+
+    checkMissingIterableValueType: false