feat(error-handling): 🚧 Creates an exception factory

This PR is just to suggest an error factory suggested in feature request jumbojett#250  It doesn't covers all exceptions because I want to know if this can help or not.  It creates an exception factory in order to throw specific exceptions and user can handle exceptions without to compare messages

src/OpenIDConnectClient.php

@@ -86,7 +86,7 @@ class OpenIDConnectExceptionFactory
     private static $codes = array(
         self::UNABLE_VERIFY_SIGNATURE => 'Unable to verify signature',
         self::TOKEN_IS_NOT_STRING => 'Error token is not a string',
-        self::TOKEN_PART_MISSING => 'Error missing part 0 in token',
+        self::TOKEN_PART_MISSING => 'Error missing part %s in token',
         self::UNABLE_DECODE_TOKEN => 'Error decoding signature from token',
         self::UNABLE_DECODE_JSON_HEADER => 'Error decoding JSON from token header',
         self::UNABLE_DECODE_JSON_JWKS_URI => 'Error decoding JSON from jwks_uri',