Rename Fut to ResponseFuture

[prasannavl]

Description

Resolves #24

Motivation and Context

Currently, the associated params of HttpService are ConnectionFuture which corresponds to connect, and the Fut which corresponds to respond.

I think it'd be better to call this ResponseFuture such that it maintains parity.

connect -> ConnectionFuture
respond -> ResponseFuture

rather than the Fut that isn't really informative or intuitive.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[secretfader]

You'll need to change the associated type in http-service-mock to satisfy CI, but other than that this change gets a 👍 from me. (It's a tiny modification with potentially huge positive impact.)

[prasannavl]

Yup. Was just working on it. This should do it

[yoshuawuyts]

Looks great, thanks!