S3 file support

Opening a meta issue for possible changes/additions to better support interacting with files on S3

• We might need something like s3path (but smaller) to interact with the filenames... using pathlib.Path('s3://my-bucket') leaves you with Path(s3:/my-bucket).
• rasterio has built-in support for strings like s3://my-bucket/my-file.tif, while using gdal bindings requires you to convert it to /vsis3/my-bucket/my-file.tif. That sounds annoying enough to find all edge cases that it might be worth the slow switchover to rasterio
• Probably a separate bigger issue related to the reader issue, but it would be useful to have hdf5 streaming capability

Start by separating the three proposals in the issue: S3 path handling, rasterio versus GDAL S3 paths, and HDF5 streaming. Read the linked s3path repository and HDF5 gist, then compare the rasterio and GDAL approaches; done requires a maintainer-approved scope rather than this broad meta issue.