Extend Python bindings with awkward-array interface

[HealthyPear]

The current Python bindings work nicely, but have the limitation that are based on numpy which doesn't like nested ragged arrays, which is all what XCDF is.

A nice project specifically built to deal with this kind of arrays is awkward-array.

If we manage to add a binding interface based on this, then and XCDF file should be basically an awkward "table" (see scikit-hep/awkward#2597).

The only limitation wrt to astropy tables is the support of units which is still under development (see scikit-hep/awkward#2468).

The metadata (in XCDF the "comments" section) might be simply loaded as an array of awkward records.