getLongRunningPoller not working if response definitions are the same between operations

[MaryGao]

We have reported similar modular issue but this issue still exists in RLC.

Say we have Foo and Bar responses and we would generate below overloadings. But if the definition of these two operations are the same or Bar is subset of Foo's, our overloading would be not working. This is because TypeScript is duck-typing it compares the definition with shape not interface names.

This usually happened in LRO operations where the initial response is the same but the final response is different. So we can't correctly predict the logical response.

export function getLongRunningPoller(
  response: FooResponse | FooDefaultResponse,
): response is FooDefaultResponse | FooLogicalResponse ;

export function getLongRunningPoller(
  response: BarResponse | BarDefaultResponse,
): response is BarDefaultResponse | BarLogicalResponse;

The same issue would happen in isUnexpected helper.