Add Composer file and add PHPCS as dev dependency

PHPCS can be used to check & format code.

https://github.com/squizlabs/PHP_CodeSniffer

Author: ravage84

composer.json

@@ -0,0 +1,13 @@
+{
+    "name": "microsoft/sql-server-samples",
+    "description": "Official Microsoft GitHub Repository containing code samples for SQL Server",
+    "type": "project",
+    "require": {
+        "php": ">=7.0.0"
+    },
+    "require-dev": {
+        "squizlabs/php_codesniffer": "^3.5"
+    },
+    "license": "MIT",
+    "minimum-stability": "stable"
+}