Feature/index create dir

[steph-ben]

When working with many GRIB files on read-only partition, we set a lot of time indexpath='' to avoid error messages. However, it's very slow because we don't use indexes at all.

This simple PR will allow us to set a particular directory for index files, by automatically create path if needed.

Example of usage :

ds = xr.open_dataset(fp, engine='cfgrib', backend_kwargs={'indexpath': '/tmp/indexes/{path}.idx'})

[FussyDuck]

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1 out of 2 committers have signed the CLA.

✅ steph-ben
❌ benchimols
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