Feature/enable fsx

[spunkedy]

• Run mix format using a recent version of Elixir :heavy_check_mark:
• Run mix dialyzer to make sure the typing is correct :heavy_check_mark:
• Run mix test to ensure no tests have broken (also please make sure you've added tests for your particular change, where appropriate). N/A

This enables the FSx endpoints, including FIPs endpoints for federal.

The endpoint list comes from:

FSx docs

Tested the configuration change with:

%ExAws.Operation.JSON{
      http_method: :POST,
      headers: [
        {"x-amz-target", "AWSSimbaAPIService_v20180301.DescribeFileSystems"},
        {"content-type", "application/x-amz-json-1.1"}
      ],
      path: "/",
      params: %{},
      data: %{},
      service: :fsx
    }

based upon this spec

[spunkedy]

this will close #950

[bernardd]

Thanks @spunkedy!

[spunkedy]

Absolutely, thanks for the quick turn around.