Convert HEASARC SciServer notebooks to the format required for HEASARC-tutorials

[DavidT3]

We haven't yet decided on how to work the SciServer tutorials into the HEASARC-tutorials repo - it seems a little silly to have both, and I think we do want the sciserver tutorials to be in the HEASARC-tutorials repo (and website).

Anyway, the HEASARC-tutorials repo requires a slightly different formatting to ensure the notebooks will execute and build properly in the Sphinx MyST setup we will be using to make the website, and they also need to be made compliant with the HEASARC-tutorials notebook template.

I'm going to do the conversion for all the notebooks and we can figure out the interplay between the existing sciserver cookbook repo and the HEASARC-tutorials.

• Getting started with IXPE data
• Analysing NICER
• NuSTAR lightcurve extraction
• RXTE lightcurve extraction
• RXTE spectral analysis with machine learning
• RXTE spectrum visualization example
• Data catalog cross match
• XMM PySAS short intro

[DavidT3]

The NuSTAR lightcurve notebook conversion is finished by dint of it being superseded by issue #80

[DavidT3]

The idea of Tess' RXTE light curve notebook will be ingested into HEASARC-tutorials, but we're going to mix things up a little and use a different source - IGR J17480–2446.

Was the subject of a press-release at one point:
https://www.nasa.gov/universe/nasas-rxte-captures-thermonuclear-behavior-of-unique-neutron-star/

Doesn't have too many observations, and looks like it exhibits some interesting time-varying behaviors!

Tess demonstrates the re-processing of RXTE data (I think so anyway from my skim) - I might pare that back to just using existing products to simplify the notebook, as I will at some point create RXTE-from-scratch tutorials.

[DavidT3]

With issue #229 and PR #230, the 'data catalog cross match' notebook has been replicated, at least in capability, so we can close this issue (even though the PR isn't merged yet).