Added __on_player_message event (#1312)

* Added __on_player_sends_message event

* Docs for chat message event

* Rename to __on_player_message

* Editor support

* Added event to event_test app

* Update docs/scarpet/api/Events.md

Co-authored-by: gnembon <41132274+gnembon@users.noreply.github.com>

docs/scarpet/resources/editors/idea/4.txt

@@ -44,5 +44,6 @@ __on_player_dies(player) ->
 __on_player_respawns(player) -> 
 __on_player_disconnects(player, reason) -> 
 __on_player_connects(player) -> 
+__on_player_message(player, message) ->
 __on_explosion(pos, power, source, causer, mode, fire) ->
 __on_explosion_outcome(pos, power, source, causer, mode, fire, blocks, entities) ->