Implement serialization of Peng-Robinson phases

[speth]

Changes proposed in this pull request

• Implement serialization of Peng-Robinson phases
• Update Redlich-Kwong serialization to save critical parameters for species where those were provided instead of R-K specific parameters
• Some formatting cleanup of the PengRobinson class
• Fix incorrect acentric factors for O2 and N2 in critical-properties.yaml

If applicable, provide an example illustrating new features this pull request is introducing

import cantera as ct
p = ct.Solution('test/data/thermo-models.yaml', 'CO2-PR')
print(p.write_yaml(skip_user_defined=True))

...
species:
  - name: CO2
    composition: {C: 1.0, O: 2.0}
    thermo:
      model: NASA7
      temperature-ranges: [200.0, 1000.0, 3500.0]
      data:
        - [2.35677352, 8.98459677e-03, -7.12356269e-06, 2.45919022e-09,
        -1.43699548e-13, -4.83719697e+04, 9.90105222]
        - [3.85746029, 4.41437026e-03, -2.21481404e-06, 5.23490188e-10,
        -4.72084164e-14, -4.8759166e+04, 2.27163806]
    equation-of-state:
      model: Peng-Robinson
      a: 3.958134e+05
      b: 0.0266275
      acentric-factor: 0.228
      binary-a:
        H2O: 7.897e+06
...

Checklist

• The pull request includes a clear description of this code change
• Commit messages have short titles and reference relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• Style & formatting of contributed code follows contributing guidelines
• The pull request is ready for review

[codecov]

Codecov Report

Merging #1180 (0d4cef3) into main (fcff592) will increase coverage by 0.05%.
The diff coverage is 96.26%.

@@            Coverage Diff             @@
##             main    #1180      +/-   ##
==========================================
+ Coverage   65.35%   65.40%   +0.05%     
==========================================
  Files         315      318       +3     
  Lines       45999    46178     +179     
  Branches    19531    19639     +108     
==========================================
+ Hits        30062    30203     +141     
- Misses      13445    13470      +25     
- Partials     2492     2505      +13     

Impacted Files	Coverage Δ
include/cantera/thermo/MixtureFugacityTP.h	0.00% <ø> (ø)
include/cantera/thermo/RedlichKwongMFTP.h	100.00% <ø> (ø)
include/cantera/thermo/ThermoPhase.h	30.57% <ø> (ø)
src/thermo/MixtureFugacityTP.cpp	37.50% <ø> (+0.13%)	⬆️
src/thermo/RedlichKwongMFTP.cpp	71.18% <88.88%> (+0.66%)	⬆️
src/thermo/PengRobinson.cpp	85.62% <98.73%> (+0.79%)	⬆️
include/cantera/thermo/PengRobinson.h	100.00% <100.00%> (ø)
src/transport/TransportBase.cpp	25.00% <0.00%> (-6.71%)	⬇️
src/base/Solution.cpp	79.51% <0.00%> (-5.53%)	⬇️
include/cantera/kinetics/Kinetics.h	36.52% <0.00%> (-2.28%)	⬇️
... and 14 more

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[decaluwe]

Thanks so much, @speth, both for the new capabilities and the significant cleanup of PengRobinson.

Everything looks good to me. I haven't downloaded and run installation to test, figuring that the test coverage would catch issues, but LMK if you'd like me to take that step.

No "real" changes below, only two comment lines that got moved that I think we'd probably be fine deleting.

[bryanwweber]

@decaluwe Is this good to merge?

[decaluwe]

LGTM - thanks, @speth