Add s3 adapter

[barbuz]

• fixes Cannot read datapackage from s3 #1596

Since it was impossible to load a Package stored on s3 this adds an adapter to the AWS Plugin that previously only had a loader.

It would be useful to merge #1632 first, as I was not able to run the tests before applying those changes.

Note that this allows loading a Package, but it is still not possible to load Resources contained in a datapackage file that are stored on s3. i.e. the following test would still fail:

@mock_s3
def test_s3_package_resource(bucket_name):
    # Write
    client = boto3.resource("s3", region_name="us-east-1")
    bucket = client.create_bucket(Bucket=bucket_name, ACL="public-read")  # type: ignore
    bucket.put_object(
        ACL="private",
        Body=open("data/package.json", "rb"),
        Bucket=bucket_name,
        ContentType="text/json",
        Key="prefix/package.json",
    )
    bucket.put_object(
        ACL="private",
        Body=open("data/table.csv", "rb"),
        Bucket=bucket_name,
        ContentType="text/csv",
        Key="prefix/table.csv",
    )

    # Read
    package = Package(f"s3://{bucket_name}/prefix/package.json")

    assert package.get_table_resource("name").read_rows() == [
        {"id": 1, "name": "english"},
        {"id": 2, "name": "中国人"},
    ]

The first issue for that is in the remote loader, that greedily captures anything that helpers.is_remote_path recognises as remote, including s3 URLs. This can easily be patched, but then I found out that for some reason those resources get assigned a scheme of file rather than a scheme of s3, so they are not loaded by the AWS loader; I was not able to find why this happens, it seems to be some dynamically generated code.

@roll you have marked that issue as "good first issue" but I ended up getting quite confused by the Plugin system when trying to solve it. Do you have any pointers that could be useful in finding what is happening to these Resource descriptors?

[roll]

Hi @barbuz, sorry for the confusion and thanks for you help!

Do you think if this one is good to go (I think it might need some documentation as well) or you would like to add support for resources as well in this PR?

The tests have been fixed so it can be tested on CI

[barbuz]

Hi! I can try to add some documentation to the AwsAdapter class.
It would be great to add support for resources as well but as I said I would need some pointers because I could not figure out how to make it work.
So if you have any suggestion on that regard please share them, otherwise I think this can be merged in and it will still be better than nothing :)