Ensure Card.collapsed and Accordion.active parameters are synced

[philippjfr]

Fixes #2005
Fixes #2006

[codecov]

Codecov Report

Merging #2009 (c1cfe35) into master (521cd34) will increase coverage by 0.01%.
The diff coverage is 97.14%.

@@            Coverage Diff             @@
##           master    #2009      +/-   ##
==========================================
+ Coverage   84.81%   84.83%   +0.01%     
==========================================
  Files         166      166              
  Lines       19996    20031      +35     
==========================================
+ Hits        16960    16993      +33     
- Misses       3036     3038       +2     

Impacted Files	Coverage Δ
panel/layout/accordion.py	88.04% <95.83%> (+3.32%)	⬆️
panel/layout/card.py	95.83% <100.00%> (+0.08%)	⬆️
panel/tests/layout/test_accordion.py	96.93% <100.00%> (+0.34%)	⬆️
panel/io/reload.py	65.88% <0.00%> (-2.36%)	⬇️
panel/widgets/input.py	95.83% <0.00%> (-0.04%)	⬇️
panel/widgets/select.py	93.51% <0.00%> (+0.02%)	⬆️
panel/tests/test_reactive.py	98.88% <0.00%> (+0.07%)	⬆️

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