Adds a matplotlib style guide notebook to gallery

[MarcSkovMadsen]

Addresses #3033

Try it out on binder

• notebook: https://mybinder.org/v2/gh/holoviz/panel/matplotlib-style?urlpath=lab/tree/examples/gallery/styles/MatplotlibStyle.ipynb
• app: https://mybinder.org/v2/gh/holoviz/panel/matplotlib-style?urlpath=panel/MatplotlibStyle

Todo

• [] Philipp to expose pn.state.theme
• [] Marc to use pn.state.theme in notebook.

Promo Material

MatplotlibStyle.mp4

[codecov]

Codecov Report

Merging #3036 (e39e433) into master (09bab95) will decrease coverage by 0.26%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3036      +/-   ##
==========================================
- Coverage   83.25%   82.99%   -0.27%     
==========================================
  Files         190      192       +2     
  Lines       24971    25477     +506     
==========================================
+ Hits        20789    21144     +355     
- Misses       4182     4333     +151     

Impacted Files	Coverage Δ
panel/models/tabulator.py	95.45% <0.00%> (-3.18%)	⬇️
panel/io/reload.py	69.23% <0.00%> (-2.20%)	⬇️
panel/io/server.py	71.94% <0.00%> (-1.70%)	⬇️
panel/tests/conftest.py	94.85% <0.00%> (-1.05%)	⬇️
panel/auth.py	39.94% <0.00%> (-0.68%)	⬇️
panel/tests/pane/test_plotly.py	98.15% <0.00%> (-0.62%)	⬇️
panel/widgets/tables.py	84.97% <0.00%> (-0.58%)	⬇️
panel/command/serve.py	39.26% <0.00%> (-0.31%)	⬇️
panel/pane/vega.py	83.04% <0.00%> (-0.30%)	⬇️
panel/template/base.py	78.43% <0.00%> (-0.28%)	⬇️
... and 34 more

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[MarcSkovMadsen]

This file will referenced the notebook for now. Please upload to s3 bucket @philippjfr .

[philippjfr]

Here's the link: https://assets.holoviews.org/panel/thumbnails/gallery/styles/matplotlib-styles.gif