Make plot_tools.OdaLightCurve more universal

[dsavchenko]

There are a lot of restrictions currently
e.g. in get_lc the RATE column is assumed, whereas data_products.LightCurveDataProduct is meant to be more universal, allowing FLUX, MAG, COUNTS columns

Plotting also seems to work only with src_name meta_data field set in data product; the name of data unit should contain exactly LC, more restrictions may occur.

@volodymyrss @andriineronov here we come back to the +- strict definition of the lightcurve product.

[volodymyrss]

We can relax assumptions in get_lc etc.

[volodymyrss]

For every code revision, we can infer that it implements certain standard.

We can even think of it as a a URI constructed like this:

https://github.com/oda-hub/oda_api/blob/ddc67e17afbe6cb9c6caab91ff0e4c3e80ff1194/oda_api/plot_tools.py#OdaLightCurve

each of these https://github.com/oda-hub/oda_api/blob/*/oda_api/plot_tools.py#OdaLightCurve are subClass of https://odahub.io/ontology/#LightCurve . (it should be written in the class I guess)

Currently, https://odahub.io/ontology/#LightCurve is not constraining in ontology. We'll add move properties there.

But it should not prevent you from developing new https://github.com/oda-hub/oda_api/blob/*/oda_api/plot_tools.py#OdaLightCurve as you see fit.

You see, this is a form of language/ontology evolution from ground-up, supported by top-down revisions which is I think more fruitful and actually more life-like than strictly top-down.

(by the way, they can be moved to a different module, plot_tools is no more appropriate)