Add warnings for PCH error

[WardBrian]

Resolves #382. Based on the same idea in cmdstanr

Submission Checklist

• Run unit tests
• Declare copyright holder and open-source license: see below

Summary

This is a (partial?) solution to #382. It produces a warning if the compile command fails for this reason, which currently directs the user to call install_cmdstan(overwrite=True).

If we believe there is merit to providing a separate rebuild_cmdstan(), I can refactor the install code to support this, but it would be largely the same as this call, I believe.

I should also mention I'm not sure how to artificially recreate this issue to test it, but the logic behind showing the warning is simple enough (based on cmdstanr) that I am pretty positive it would work

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company):
Simons Foundation

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)

[codecov-commenter]

Codecov Report

Merging #421 (45b1eba) into develop (ea0f3f2) will decrease coverage by 0.07%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #421      +/-   ##
===========================================
- Coverage    77.31%   77.24%   -0.08%     
===========================================
  Files           27       27              
  Lines         8556     8568      +12     
===========================================
+ Hits          6615     6618       +3     
- Misses        1941     1950       +9     

Impacted Files	Coverage Δ
a/cmdstanpy/cmdstanpy/cmdstanpy/model.py	80.43% <0.00%> (-0.61%)	⬇️
cmdstanpy/cmdstanpy/model.py	79.34% <0.00%> (-0.60%)	⬇️
...runner/work/cmdstanpy/cmdstanpy/cmdstanpy/model.py	79.34% <0.00%> (-0.60%)	⬇️

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[mitzimorris]

LGTM!