feat: Add DSPDetails for grouped players

music_assistant_models/streamdetails.py

@@ -80,7 +80,12 @@ class StreamDetails(DataClassDictMixin):
     strip_silence_begin: bool = False
     strip_silence_end: bool = False
     stream_error: bool | None = None
+    # In case of grouped playback, this will contain the DSP details for
+    # the leader (keep in mind that PlayerGroups has no leader!)
     dsp: DSPDetails | None = None
+    # In case of grouped playback, this will contain the DSP details for
+    # all other players of the group (indexed by player_id)
+    dsp_grouped_childs: dict[str, DSPDetails] | None = None
 
     def __str__(self) -> str:
         """Return pretty printable string of object."""