use obstore instead of fsspec for xarray backend reader

[hrodmn]

Now that obstore is becoming more stable we could probably use it in place of fsspec + s3fs!

cc @sharkinsspatial @abarciauskas-bgse

[vincentsarago]

same as developmentseed/titiler#1084

[chuckwondo]

@hrodmn, I mentioned this in #74, but it bears repeating for this issue:

I don't think we'll be able to eliminate fsspec for the h5netcdf engine, but we can at least remove earthaccess. Moving to obstore should allow us to drop the s3fs dependency, but not the fsspec dependency. While we should be able to leverage obstore.fsspec.FsspecStore for the h5netcdf engine, use of obstore.fsspec.FsspecStore does require fsspec as a dependency.

[chuckwondo]

@hrodmn, based on your suggestion to look at obspec-utils in #74 (comment), it looks like we may indeed be able to drop both fsspec and s3fs, if I'm reading things correct, yes?

[hrodmn]

I believe so. Instead of doing [pseudocode] xr.open_dataset(fs.open(..., s3_credentials=s3_credentials)) I think we could create an S3Store with the EDL credential provider, then pass that to one of the obspec-utils readers (which can be opened directly with xr.open_dataset). I'm not sure how the obstore credential provider would interact with the EDL credentials cache system, though.

[chuckwondo]

I believe so. Instead of doing [pseudocode] xr.open_dataset(fs.open(..., s3_credentials=s3_credentials)) I think we could create an S3Store with the EDL credential provider, then pass that to one of the obspec-utils readers (which can be opened directly with xr.open_dataset). I'm not sure how the obstore credential provider would interact with the EDL credentials cache system, though.

The out-of-box obstore credential provider would not recognize our cached credentials. However, we can simply implement our own credential provider that makes use of the cache and pass that in instead.

[chuckwondo]

See #79

That PR is quite out of date, but we may be able to salvage a bit of the logic there for this issue.

[hrodmn]

Closed by #145