Ingest NCM XAS simulations

[danielballan]

This is item 5i in the Google doc. Data owner is Yiming.

Data comprises.TM K-edge (from Yiming), TM-L edge, O K-edge (from Haili).

There are two kinds of data here:

• the simulated structure (chi file)
• the simulated spectrum

For a given simulated structure, there may be multiple simulated spectra; that is, there is a one-to-many relationship between structure and spectra. We can encode this association in the metadataof each spectrum:{"structure": <uid of structure>}. Later, this would be an ideal use case for references but we don't have that feature availabe in aimmdb yet.