Implement auto_grow on TextAreaInput

[philippjfr]

Supersedes #5591

[codecov]

Codecov Report

Merging #5592 (d24184b) into main (84a3672) will increase coverage by 1.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #5592      +/-   ##
==========================================
+ Coverage   82.47%   83.52%   +1.05%     
==========================================
  Files         275      275              
  Lines       39480    39519      +39     
==========================================
+ Hits        32560    33009     +449     
+ Misses       6920     6510     -410     

Flag	Coverage Δ
ui-tests	40.80% <100.00%> (+2.16%)	⬆️
unitexamples-tests	73.49% <34.88%> (-0.05%)	⬇️

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Files	Coverage Δ
panel/models/__init__.py	100.00% <ø> (ø)
panel/models/widgets.py	100.00% <100.00%> (ø)
panel/tests/ui/widgets/test_input.py	99.47% <100.00%> (+0.04%)	⬆️
panel/widgets/input.py	95.44% <100.00%> (+0.03%)	⬆️

... and 22 files with indirect coverage changes

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