Apply Template theme to HoloViews plots

[philippjfr]

Fixes #1764

[codecov]

Codecov Report

Merging #1767 (163bb0c) into master (06530a0) will increase coverage by 0.35%.
The diff coverage is 83.60%.

@@            Coverage Diff             @@
##           master    #1767      +/-   ##
==========================================
+ Coverage   84.93%   85.28%   +0.35%     
==========================================
  Files         151      151              
  Lines       17420    17882     +462     
==========================================
+ Hits        14796    15251     +455     
- Misses       2624     2631       +7     

Impacted Files	Coverage Δ
panel/config.py	51.21% <ø> (+5.97%)	⬆️
panel/io/location.py	84.40% <ø> (+1.07%)	⬆️
panel/io/state.py	51.87% <50.00%> (+2.99%)	⬆️
panel/viewable.py	71.54% <50.00%> (-1.77%)	⬇️
panel/pane/holoviews.py	84.04% <52.94%> (-1.03%)	⬇️
panel/template/base.py	72.75% <77.77%> (+0.39%)	⬆️
panel/widgets/slider.py	93.95% <81.81%> (+2.25%)	⬆️
panel/io/server.py	65.17% <100.00%> (ø)
panel/layout/card.py	95.74% <100.00%> (ø)
panel/layout/grid.py	76.82% <100.00%> (+0.57%)	⬆️
... and 83 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update df1f435...163bb0c. Read the comment docs.