Add status code modifier for IntoResponse

[tirr-c]

Description

This PR adds a provided method, with_status, to IntoResponse. This method returns a wrapper around the value that modifies response status code.

Motivation and Context

Part of #116. This change makes returning Json error easier.

I'm not sure if this is the right direction, though.

How Has This Been Tested?

I've added a unit test that runs with_status on &'static str, then compares the final status code.

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.

[aturon]

This definitely seems worth trying! I'm not sure ultimately what's going to work best on the error path, so personally I'm inclined to merge this for the sake of experimentation.