Optimize rendering of ChatMessage

[philippjfr]

Attempt at improving #6064

%%timeit
pn.chat.ChatMessage('Some content', user='user')

Before:

19.6 ms ± 591 µs per loop (mean ± std. dev. of 7 runs, 10 loops each

After:

10.9 ms ± 138 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

The main performance gains here came from avoiding use of ParamMethod and instead favoring manual watch callbacks.

Note those numbers also already account for the changes in: holoviz/param#893

Without that it goes from:

21.6 ms ± 974 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)

to:

11.7 ms ± 280 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (208fb7b) 84.63% compared to head (a97358f) 84.64%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6069      +/-   ##
==========================================
+ Coverage   84.63%   84.64%   +0.01%     
==========================================
  Files         295      295              
  Lines       43977    44003      +26     
==========================================
+ Hits        37219    37246      +27     
+ Misses       6758     6757       -1     

Flag	Coverage Δ
ui-tests	40.61% <9.21%> (-0.03%)	⬇️
unitexamples-tests	72.73% <100.00%> (+0.01%)	⬆️

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[ahuang11]

There seems to be some weird indentation after these changes:

After removing width 100% - 15px, it's back to normal

[ahuang11]

Some flickering seems to occur again (also I tried to fix the weird indentation, but it crops the heart):

Screen.Recording.2023-12-17.at.4.48.40.PM.mov

On main:

Screen.Recording.2023-12-17.at.4.50.05.PM.mov