Forward not ChatFeed params to message_params

[ahuang11]

Makes it possible to do:

import panel as pn

pn.chat.ChatInterface(
    reaction_icons={"like": "thumb-up", "dislike": "thumb-down", "favorite": "heart"}, reactions=["like"]
).servable()

Rather than awkwardly nesting dicts:

import panel as pn

pn.chat.ChatInterface(
    message_params={"reaction_icons": {"like": "thumb-up", "dislike": "thumb-down", "favorite": "heart"}, "reactions": ["like"]}
).servable()

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5b89692) 84.66% compared to head (214d04c) 84.67%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6089   +/-   ##
=======================================
  Coverage   84.66%   84.67%           
=======================================
  Files         296      296           
  Lines       44057    44070   +13     
=======================================
+ Hits        37302    37315   +13     
  Misses       6755     6755           

Flag	Coverage Δ
ui-tests	40.62% <7.69%> (-0.01%)	⬇️
unitexamples-tests	72.75% <100.00%> (+<0.01%)	⬆️

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