Remove isReadable/HDFVersion from NexusHDF5Descriptor and try/catch instead

[rosswhitfield]

Description of work

Follow on from #38786, this changes how which Nexus Descriptor is used.

This removes the isReadable or HDFVersion functions and uses H5::H5File::isHdf5 where possible, other handle any exceptions.

Summary of work

Refs #38332

Further detail of work

To test:

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[peterfpeterson]

I'm not a huge fan of using exceptions in the standard operation for an if/else sort of thing, but the code is indeed easier to follow in this new form.