Get python to parity with R updates

[jhofman]

@chisingh, once @willdebras merges documentation, can you take a look to see what's new in R?

some of the custom animation stuff (mean, median) should come "for free" without any or much spec update. other stuff like quantile will require some pipeline parsing on the python side. (@willdebras or @giorgi-ghviniashvili, can you link an example spec for quantile here?)

let's capture a list of what needs to be done, then we can go about doing it :)

[willdebras]

@chisingh, apologies for the delay on this. These quantile specs are fully updated:

https://github.com/microsoft/datamations/blob/main/sandbox/custom_animations/custom-animations-quantile-R.json

The generation on the R side has been updated to do the following:

• Parses specific summary expressions instead of just calculating the summary verb (i.e. capturing and creating data for the parameter provided to quantile(Salary, 0.01).
• Adds a meta spec that captures these differences so Giorgi's custom animation code will run on it. You can see this definition on the following line:

https://github.com/microsoft/datamations/blob/main/sandbox/custom_animations/custom-animations-quantile-R.json#L846