[newchem-cpp] transcribe lookup_rate_1d_g

[mabruzzo]

This PR should be reviewed after #386 and #411 are merged

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This PR transcribes lookup_rate_1d_g to C++. This is pretty self-explanatory.

At the moment, this is pretty much a raw transcription (that was reformatted by clang-format). The following needs to be done before it's ready for review:

• replace all of the internal calls that directly try to call fortran functions with calls to the nice c++ wrappers
• clean up the signature (make it more like grackle::impl::fortran_wrapper::lookup_cool_rates1d_g)
• remove grackle::impl::fortran_wrapper::lookup_cool_rates1d_g (and replace all calls to it with calls to grackle::impl::lookup_cool_rates1d_g). We probably also want to copy over all the notes in the docstring signature
• fix all of the indexing (get rid of the -1 nonsense)
• clean up some of the internal comments

Plans for followup PRs:

The C++ implementation can be cleaned up in a number of ways:

• we should obviously replace the simple 1D interpolation for the 85 standard collisional rates to make use of for-loops that iterate over rates
• we should factor out logic for computing different kinds of rates into different helper functions
• we should create a nice container to track all the scratch-space (so we don't re-allocate it every time we call the function)
• we should refactor the logic for computing k13dd to reduce the size of the temporary buffers
• I would also really like to store the sublimation temperatures for each dust species in a table (ideally created during initialize_chemistry_data) that is indexed by the OnlyGrainSpLUT enum so we can convert all that logic to much simpler loops. (I want to use loops for all dust-related stuff, but I haven't looked to see how plausible that is)

Most (all?) of these changes are implemented in followups PRs: #415, #416, #428, #429

[mabruzzo]

Huh, well I just pushed a commit to fix the merge conflict and it's not showing up. I guess GitHub is struggling today

EDIT: nevermind, it all appears to have worked out