Support Page<T> in LRO response type in TypeSpec in RLC

[lirenhe]

This issue was reported in dotnet Azure/autorest.csharp#2905, but I expect JS RLC should also support this.
Below is an example TypeSpec with LRO POST action that generates a pageable collection of file URIs.

  #suppress "@azure-tools/cadl-azure-core/use-standard-operations" "ADP data-plane API uses custom LRO response template the LRO actions."
  @doc("Initiates the process of generating SAS signed URIs for accessing the data-stream files.")
  @extension("x-ms-long-running-operation", true)
  @asyncOperationOptions("location")
  @pollingOperation(LongRunningOperationStatus)
  generate is CustomLongRunningResourceCollectionAction<
    DataStreamFile,
    {},
    Page<DataStreamFile>
  >;

[deyaaeldeen]

Related to #944

[qiaozha]

Have some document and verification work on this.

[lirenhe]

Let's do the investigation to understand its impact for the existing API design in Dt.