KTOR-2143 Fixed CIO server wrong requested URL

[LichtHund]

trafficstars

Subsystem CIO Server

Motivation CIO server would use wrong request URL, causing OAuth to return redirect_uri_mismatch. KTOR-2143.

Solution Reverse host's get condition logic to be like Netty and Jetty.

[Stexxe]

@ipsk please add a test.

[rsinukov]

Will be fixed in #3122