Add Legacy HTTPlug Message Implementation

Author: zanbaldwin

composer.json

@@ -22,6 +22,7 @@
     "require-dev": {
         "phpunit/phpunit": "^8.0 || ^9.0",
         "guzzlehttp/guzzle": "^7",
+        "php-http/message-factory": "^1.1",
         "php-http/mock-client": "^1.0",
         "friendsofphp/php-cs-fixer": "^3.0",
         "phpstan/phpstan": "^1.2"