Incorporating the LMR-R mixture rule into Cantera for the first time

[pjsingal]

Changes proposed in this pull request

• LmrRate.cpp and LmrRate.h allow for vastly improved consideration of the mixture-dependent aspect of the rate constants for complex-forming ("pressure-dependent") reactions, using the new LMR-R mixture theory developed by the Burke Lab at Columbia University

• This code builds, runs, and produces results that have been validated and peer-reviewed

• LMR-R can handle three different representations of the pressure-dependent aspect of complex-forming reactions: Troe, PLOG, and Chebyshev

• LMR-R calculates the mixture-dependent aspect using temperature-dependent third-body efficiencies that have been supplied by the user for at least one collider - these parameters can be provided in either relative or absolute terms, as long as the user's choice is consistent for all colliders in a given reaction

• Description of the theory and instructions for implementation have been added to rate-constants.md and reactions.rst, respectively

• Four new Python examples have been added

Checklist

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

[codecov]

Codecov Report

Attention: Patch coverage is 0.78740% with 252 lines in your changes missing coverage. Please review.

Project coverage is 72.87%. Comparing base (ec0cfdb) to head (0eb6e58).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/kinetics/LinearBurkeRate.cpp	0.00%	224 Missing ⚠️
include/cantera/kinetics/LinearBurkeRate.h	0.00%	15 Missing ⚠️
interfaces/cython/cantera/reaction.pyx	14.28%	12 Missing ⚠️
src/kinetics/ReactionRateFactory.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1710      +/-   ##
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- Coverage   73.23%   72.87%   -0.37%     
==========================================
  Files         381      383       +2     
  Lines       54375    54616     +241     
  Branches     9251     9282      +31     
==========================================
- Hits        39823    39802      -21     
- Misses      11580    11832     +252     
- Partials     2972     2982      +10     

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