Cannot parse AWS S3 HTTP URLs without region

[kylebarron]

Describe the bug

The AmazonS3Builder cannot parse this URL:

https://bucket.s3.amazonaws.com/path

It's preferred for URLs to include regions in the URL, like https://[bucket].s3.[region].amazonaws.com, but we should still allow the old-style URL.

To Reproduce

This test fails without any changes

        let mut builder = AmazonS3Builder::new();
        builder
            .parse_url("https://bucket.s3.amazonaws.com")
            .unwrap();
        assert_eq!(builder.bucket_name, Some("bucket".to_string()));
        assert!(builder.virtual_hosted_style_request.get().unwrap());

Expected behavior

Should parse URL

Additional context

ref developmentseed/obstore#589

[tustvold]

I think we need to get the region from somewhere, unless it is implied to be us-east-1?

[kylebarron]

I think it's fine to handle it in the same way we handle bucket_name already. That is, we should extract whatever information we can from a valid URL, and let the user pass in any extra information they know about.

So a user could do

let s3 = AmazonS3Builder::new()
    .with_url("https://bucket.s3.amazonaws.com/")
    .with_region("us-west-2")
    .build();