Change Message.application type to MessageApplication

Co-authored-by: Danny <1695103+Rapptz@users.noreply.github.com>

docs/api.rst

@@ -4255,6 +4255,14 @@ PartialMessage
 .. autoclass:: PartialMessage
     :members:
 
+MessageApplication
+~~~~~~~~~~~~~~~~~~~
+
+.. attributetable:: MessageApplication
+
+.. autoclass:: MessageApplication
+    :members:
+
 Intents
 ~~~~~~~~~~
 

docs/migrating.rst

@@ -1229,6 +1229,8 @@ The following changes have been made:
 
 - :attr:`File.filename` will no longer be ``None``, in situations where previously this was the case the filename is set to `'untitled'`.
 
+- :attr:`Message.application` will no longer be a raw `dict` of the API payload and now returns an instance of :class:`MessageApplication`.
+
 :meth:`VoiceProtocol.connect` signature changes.
 --------------------------------------------------