Add SOLO RPW spectrogram support

[samaloney]

Description

Fixes #55 adding support for some SOLO//RPW data

import sunpy_soar
from astropy.time import Time
from astropy.visualization import ImageNormalize, PercentileInterval
from sunpy_soar.attrs import Identifier
from sunpy.net import Fido, attrs as a
from matplotlib import pyplot as plt

from radiospectra.spectrogram import Spectrogram

query = Fido.search(a.Time('2020-07-11', '2020-07-11 23:59'),
                    a.Instrument('RPW'), a.Level(2), Identifier('RPW-HFR-SURV'))
downloaded = Fido.fetch(query[0])
spec = Spectrogram(downloaded[0])

fig, ax = plt.subplots()
norm = ImageNormalize(spec[0].data, interval=PercentileInterval(97.5))
spec[0].plot(norm=norm, axes=ax)
ax.set_xlim([Time('2020-07-11 2:00').datetime, Time('2020-07-11 3:00').datetime])
ax.semilogy()

[samaloney]

This code doesn't work on all RPW spectra need to test if any of acg1 or acg2 and use one or both accordingly

[hayesla]

is this the correct thing to be indexing?

Is the idea to find CH1 and CH2 here?

[nabobalis]

Probably want more source tests?

[nabobalis]

Online fail is very real.

[nabobalis]

Will it come back?

[samaloney]

Nope the job of processing/hosting has moved to a different group/institute and the data is now only available on the CDPP and I'm not sure how to search that via an API also I think the files are in CDF format another proprietary format .B3E? I'll add another change log to document the removal of the server and hence code.

[nabobalis]

So we should remove these tests and the client for it?

[samaloney]

Yea I need to check where the data can be obtained and in what formats so want to leave the code until I figure that out, only skipped the tests for the CI really.