Extend the Python interface to expose Reaction & Rate Law objects

[ecisneros8]

This PR extends the existing Python interface to expose Reaction & RateLaw, as well as a few more Mixture properties.

Particular properties that the PR aims to expose are:

• Reactant and product indices;
• Arrhenius parameters;
• The temperature (translational, electron, and T -- Tv geometric mean) at which each rate law is evaluated.

To propagate this information through to Python, most classes in the Kinetics namespace are modified. A major change within this namespace is that:

• Rate law temperature is now encoded with an enum in kinetics/ReactionType.h. The map between rate law and temperature is also encoded in kinetics/ReactionType.h. In this way, a Reaction encapsulates its rate law temperature at instantiation.