Permit selection of specific Accept header values in "Send API Request"

[SunsetFi]

User Story Description

As an API validator,

I want to run API requests against specific Accept header media types,

so I can validate the server sends back the appropriately formatted data.

Acceptance Criteria

• [ ] The 'Send API Request' button sends an Accept header equal to the media type selected in the Body description's media type dropdown.

Sprint Ready Checklist

• [ ] Acceptance criteria defined
• [ ] Team understands acceptance criteria
• [ ] Team has defined solution / steps to satisfy acceptance criteria
• [ ] Acceptance criteria is verifiable / testable
• [ ] External / 3rd Party dependencies identified

[SunsetFi]

The current behavior is to send an Accept header containing every documented return type (eg: Accept: foo/bar foo/baz). In practice, this makes our server choose the first entry. This prevents us from testing that the format for the alternate media types are respected.