[feature] added missing event types (#700)

* added missing event types

* added conversion event types

* added USER_ACCOUNT_CLOSED

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Co-authored-by: Iulian Masar <iulian.masar@codegile.com>

Author: iulian03

MangoPay/EventType.php

@@ -101,4 +101,14 @@ class EventType
     const RecipientActive = "RECIPIENT_ACTIVE";
     const RecipientCanceled = "RECIPIENT_CANCELED";
     const RecipientDeactivated = "RECIPIENT_DEACTIVATED";
+    const UserAccountValidationAsked = "USER_ACCOUNT_VALIDATION_ASKED";
+    const UserAccountActivated = "USER_ACCOUNT_ACTIVATED";
+    const UserAccountClosed = "USER_ACCOUNT_CLOSED";
+    const InstantConversionCreated = "INSTANT_CONVERSION_CREATED";
+    const InstantConversionSucceeded = "INSTANT_CONVERSION_SUCCEEDED";
+    const InstantConversionFailed = "INSTANT_CONVERSION_FAILED";
+    const QuotedConversionCreated = "QUOTED_CONVERSION_CREATED";
+    const QuotedConversionSucceeded = "QUOTED_CONVERSION_SUCCEEDED";
+    const QuotedConversionFailed = "QUOTED_CONVERSION_FAILED";
+
 }