Dingo integration

This merge request extends PESummary to read HDF5 output files from Dingo.

Main changes

• Add pesummary.core.file.formats.dingo and pesummary.gw.file.formats.dingo modules, which are based closely on their Bilby counterparts. These use the Dingo Result class to load the HDF5 file and access its contents. The Result class has specific methods to return the samples, prior, and relevant metadata for PESummary.
• Modify pesummary.core.file.read to have a function to check whether a file is a Dingo HDF5 file.
• Add Dingo as an "extras" dependency for PESummary.

Comments

• Currently there is a bug in PESummary that overwrites the metadata from the HDF5 file (e.g., https://git.ligo.org/lscsoft/pesummary/-/blob/master/pesummary/gw/conversions/init.py#L345-360) but once fixed, the Dingo metadata should be loaded.
• The merge request does not implement loading of event strain data or PSDs into PESummary.