Add support for Tabulator.title_formatters

[philippjfr]

Addresses #5417

[codecov]

Codecov Report

Merging #5421 (b93c225) into main (2f1e42a) will decrease coverage by 10.08%.
Report is 1 commits behind head on main.
The diff coverage is 50.00%.

@@             Coverage Diff             @@
##             main    #5421       +/-   ##
===========================================
- Coverage   82.75%   72.67%   -10.08%     
===========================================
  Files         274      274               
  Lines       39897    39905        +8     
===========================================
- Hits        33015    29000     -4015     
- Misses       6882    10905     +4023     

Flag	Coverage Δ
ui-tests	?
unitexamples-tests	72.67% <50.00%> (-0.01%)	⬇️

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Files Changed	Coverage Δ
panel/widgets/tables.py	87.56% <50.00%> (-1.60%)	⬇️

... and 57 files with indirect coverage changes

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