add xarray-erddap entry-point

[ocefpaf]

I'm still not sure if this should be part of erddapy or a stand-alone plugin. I'll leave this one as a draft for now. When re-visiting we need:

• Docs/examples
• Unittests
• Expand datasets Server stress tests: griddap, opendap, slices, etc. Try to find possible corner cases, hypothesis-style
• Implement both quoted and unquoted URL support. ERDDAP webpages always return quoted URLs, but users may try to write unquoted some URLs by hand.
• Check xarray's guess_can_open, see https://docs.xarray.dev/en/latest/generated/xarray.backends.BackendEntrypoint.html

[abkfenris]

So far it looks largely small enough that I don't see a great reason not to have the engine in this repo.

[ocefpaf]

So far it looks largely small enough that I don't see a great reason not to have the engine in this repo.

The reason was.... A matter of taste. Some folks are against erddapy and do not want to install it. I don't know why 🤷🏽‍♂️ . My original intent was to give those folks an option of using this without knowing they are using erddapy. Anyway, I don't think I care about this anymore and this will probably be its home.

PS: it should not get bigger than that BTW. It larger uses erddapy under the hood. This mostly makes the .to_xarray() an xarray dataset opener via an erntry-point.

[ocefpaf]

OK Got all the feedback we needed here. Merging this. Thanks all that responded here or elsewhere!