Add --warm option to panel serve

[philippjfr]

Allows executing scripts on startup to ensure the caches are warmed up

[codecov]

Codecov Report

Merging #1971 (9d37f4c) into master (2cb9d02) will decrease coverage by 0.02%.
The diff coverage is 16.66%.

@@            Coverage Diff             @@
##           master    #1971      +/-   ##
==========================================
- Coverage   84.87%   84.85%   -0.03%     
==========================================
  Files         154      154              
  Lines       19122    19128       +6     
==========================================
+ Hits        16230    16231       +1     
- Misses       2892     2897       +5     

Impacted Files	Coverage Δ
panel/command/serve.py	17.59% <16.66%> (-0.06%)	⬇️

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[MarcSkovMadsen]

Remember to include a warm option to panel.serve @philippjfr :-)

[philippjfr]

I guess I could but if you're already using panel.serve then you are already running a script which can much more effectively "warm up" the session by populating the pn.state.cache and running the desired imports. Do you still think it's useful?

[MarcSkovMadsen]

In my experience having the same options from panel serve and panel.serve is what is by some users (me) expected. It’s confusing when there is a discrepancy.

but i can see here that it might not be needed.