R1- and DL0-waveform data model

[jlenain]

In ctapipe 0.21, the expected shape of R1 and DL0 waveforms changed from (n_pixels, n_samples) to be always (n_channels, n_pixels, n_samples) (see https://ctapipe.readthedocs.io/en/latest/changelog.html#id50).

At the moment, ctapipe_io_nectarcam is not compatible with the ctapipe version v0.24 pinned to it in this respect, as explained in the issue #81.

This PR proposes a fix to this data model change, as well as, incidentally, a fix for the issue #80.

Note: we should be careful in propagating these changes in nectarchain as well, presumably by un-doing part of the PR cta-observatory/nectarchain#191.

[codecov]

Codecov Report

❌ Patch coverage is 95.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.76%. Comparing base (fd555fc) to head (a83064b).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ctapipe_io_nectarcam/__init__.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #85      +/-   ##
==========================================
+ Coverage   84.74%   84.76%   +0.02%     
==========================================
  Files           7        7              
  Lines         957      965       +8     
==========================================
+ Hits          811      818       +7     
- Misses        146      147       +1     

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