Add support for rendering inside PyScript Next

[philippjfr]

For PyScript Next support we need to do a few things:

1. Detect if we are in a worker and then patch the js.document and js.Bokeh objects
2. Ensure that we act like we are on the main thread even though we are on the worker (since PyScript now transparently handles message passing between the two).

[codecov]

Codecov Report

Attention: 17 lines in your changes are missing coverage. Please review.

Comparison is base (96f0d5a) 84.16% compared to head (91f2bdc) 72.38%.

Files	Patch %	Lines
panel/io/pyodide.py	0.00%	15 Missing ⚠️
panel/viewable.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5911       +/-   ##
===========================================
- Coverage   84.16%   72.38%   -11.78%     
===========================================
  Files         291      291               
  Lines       42779    42786        +7     
===========================================
- Hits        36005    30971     -5034     
- Misses       6774    11815     +5041     

Flag	Coverage Δ
ui-tests	?
unitexamples-tests	72.38% <0.00%> (-0.06%)	⬇️

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[MarcSkovMadsen]

I believe the template also needs an update. You can use <pyscript> but it should be <script type="py"> etc. now.

[philippjfr]

Indeed, that'll land in 1.4.0. Wanted to get this into 1.3.2 since it was such a tiny fix. It also relies on absolute bleeding edge of pyscript core, since we had to resolve some issues that were uncovered by the Panel Python <-> JS message passing dance.