Added fullpath to jupyter_server_extension

[hoxbro]

I noticed I couldn't get the Panel widget in jupyter lab to work in a non-base conda environment.

With the output in my terminal:

The error is because ~ is present in the path and when os.path.abspath is used it gives a wrong result.

path = "~/hello_there.mp4"
a_path = os.path.abspath(path)
ae_path = os.path.abspath(os.path.expanduser(path))
path, a_path, ae_path

The abspath command is called from bokeh and a fix should be implemented there too.

[codecov]

Codecov Report

Merging #3270 (6bc3290) into master (37c4044) will decrease coverage by 0.01%.
The diff coverage is 60.00%.

@@            Coverage Diff             @@
##           master    #3270      +/-   ##
==========================================
- Coverage   83.14%   83.13%   -0.02%     
==========================================
  Files         195      195              
  Lines       26030    26031       +1     
==========================================
- Hits        21643    21641       -2     
- Misses       4387     4390       +3     

Impacted Files	Coverage Δ
panel/io/jupyter_server_extension.py	0.00% <0.00%> (ø)
panel/param.py	86.66% <0.00%> (-0.15%)	⬇️
panel/command/serve.py	37.27% <50.00%> (+0.28%)	⬆️
panel/widgets/file_selector.py	84.52% <83.33%> (+0.09%)	⬆️
panel/io/reload.py	69.56% <100.00%> (-1.87%)	⬇️
panel/io/server.py	80.19% <100.00%> (ø)
panel/util.py	84.98% <100.00%> (+0.11%)	⬆️
panel/tests/command/test_serve.py	83.54% <0.00%> (-1.46%)	⬇️
panel/io/state.py	69.11% <0.00%> (-0.23%)	⬇️
... and 1 more

---

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[philippjfr]

This is great thank you! I notice you added a utility but aren't using it consistently yet.

[hoxbro]

I only have it in panel/io/jupyter_server_extension.py to avoid long lines.

Then I just searched for abspath and updated it with expanduser because it was the easiest thing to do.

If you want, I can move the functions into a utils file and call it consistently.

[philippjfr]

If you want, I can move the functions into a utils file and call it consistently.

Seems sensible.

[hoxbro]

This is outside the panel module so I chose to keep it.

[hoxbro]

Done.

Just to be transparent, I have not changed lines where something like os.path.abspath(__file__) has been used.