on_thread_create event (Pycord-Development#1285)

* Ability to diff between new & joined threads

+ docs

* Update discord/state.py

Co-authored-by: krittick <ben@krittick.net>

discord/state.py

@@ -897,7 +897,10 @@ def parse_thread_create(self, data) -> None:
         has_thread = guild.get_thread(thread.id)
         guild._add_thread(thread)
         if not has_thread:
-            self.dispatch("thread_join", thread)
+            if data.get("newly_created"):
+                self.dispatch("thread_create", thread)
+            else:
+                self.dispatch("thread_join", thread)
 
     def parse_thread_update(self, data) -> None:
         guild_id = int(data["guild_id"])

docs/api.rst

@@ -899,8 +899,7 @@ to handle it, which defaults to print a traceback and ignoring the exception.
 
 .. function:: on_thread_join(thread)
 
-    Called whenever a thread is joined or created. Note that from the API's perspective there is no way to
-    differentiate between a thread being created or the bot joining a thread.
+    Called whenever a thread is joined.
 
     Note that you can get the guild from :attr:`Thread.guild`.
 
@@ -911,6 +910,19 @@ to handle it, which defaults to print a traceback and ignoring the exception.
     :param thread: The thread that got joined.
     :type thread: :class:`Thread`
 
+.. function:: on_thread_create(thread)
+
+    Called whenever a thread is created.
+
+    Note that you can get the guild from :attr:`Thread.guild`.
+
+    This requires :attr:`Intents.guilds` to be enabled.
+
+    .. versionadded:: 2.0
+
+    :param thread: The thread that got created.
+    :type thread: :class:`Thread`
+
 .. function:: on_thread_remove(thread)
 
     Called whenever a thread is removed. This is different from a thread being deleted.