Remove s3-server and dependencies

[brainstorm]

Fixes #131

[mmalenic]

I don't think this code actually runs the tests, and they haven't been running for a while, as the test closure is never awaited! 😮 (my bad!)

This would be a good one for clippy or rustc to lint! It could be a bug, because Future is labelled with must_use.

With the changes to actually get the tests to run, the following tests are currently failing:

storage::aws::tests::url_of_existing_key
storage::aws::tests::url_of_non_existing_key
storage::aws::tests::url_with_specified_open_ended_range
storage::aws::tests::url_with_specified_range

url_of_existing_key, url_with_specified_open_ended_range and url_with_specified_range should be easy to fix as they just need an adjustment url.starts_with assertion.

For example, changing:

assert!(result
  .url
  .starts_with(&format!("http://localhost:8014/{}/{}", "folder", "key2")));

to:

assert!(result
  .url
  .starts_with(&format!("http://folder.localhost:8014/{}", "key2")));

And the byte ranges from bytes=7-9 to bytes=7-8 for url_with_specified_range should fix them.

However, url_of_non_existing_key might need a bit more investigation.