Updated json pane to accept single quote

[hoxbro]

Fixes #1798

Trying to use literal_eval for the object and then json.dumps. This PR also makes it possible to be more flexible with the object.

The only thing I'm not completely sure about is if overlook something with the removal of .replace(/(\r\n|\n|\r)/gm, "").

import panel as pn

json1 = pn.pane.JSON(object={"test": "can't show this"})
json2 = pn.pane.JSON(object=["can't show this"])
json3 = pn.pane.JSON(object="can't show this")
json4 = pn.pane.JSON(object="can show this")
json5 = pn.pane.JSON(object='{"b": 3}')
json6 = pn.pane.JSON(object="{'b': 3}")

pn.Column(json1, json2, json3, json4, json5, json6).servable()

Without the PR	With the PR (literal_eval)	With the PR (json.loads)

[codecov]

Codecov Report

Merging #2143 (1b3f7f1) into master (4533a60) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2143      +/-   ##
==========================================
+ Coverage   83.80%   83.81%   +0.01%     
==========================================
  Files         182      182              
  Lines       21658    21672      +14     
==========================================
+ Hits        18151    18165      +14     
  Misses       3507     3507              

Impacted Files	Coverage Δ
panel/pane/markup.py	97.19% <100.00%> (+0.03%)	⬆️
panel/tests/pane/test_markup.py	99.33% <100.00%> (+0.05%)	⬆️

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