Add WaitForAttribute(attributeName, targetValue, timeout, cancellationToken)
to InboundScriptHost.RouteTarget and SandboxInboundScriptHost.RouteTarget,
mirroring the shipped runtime signature in RouteHelper. Eliminates the false
CS error the editor raised against valid Route.To("X").WaitForAttribute(...)
calls in inbound API method scripts. Test asserts the call diagnoses clean
under ScriptKind.InboundApi.
Joseph Doherty
bee295d3ee