Adding Lorentz/BMS_transformation classes and tests

[keefemitman]

This includes code for Lorentz_transformation and BMS_transformation classes. For each of these two classes, you can reorder, invert, and compose transformations. The motivation behind this is for when we might want to easily transition between the superrest frame and the PN BMS frame, e.g., for future surrogate modeling. The main ideas behind this code are from Spinors and Spacetime, Volume 1, Chapters 1.2/1.3 as well as the latter parts of DOI:10.1063/1.1705135.

(The main parts of this code work, but there are parts I plan on improving after I return from vacation on September 5th).

@moble @duetosymmetry

[duetosymmetry]

TODO: Also update the code in WaveformGrid. The code for computing the transformed grid is common to both WaveformGrid and AsymptoticBondiData. Should this be factored out?

[keefemitman]

What's the best way to incorporate this .TeX file into the docs? https://www.overleaf.com/6964495134vvzdnkwnwkhv

[moble]

What's the best way to incorporate this .TeX file into the docs? overleaf.com/6964495134vvzdnkwnwkhv

I can't see the file to see how complicated it is, but maybe use pandoc to convert to .rst, then include it in scri/docs like the tutorials Dante wrote up?

[keefemitman]

@moble do you want me to write the test function for the boosts that we talked about?

[keefemitman]

@moble just bumping this

[moble]

Thanks @keefemitman and @duetosymmetry