Models are not exported to top-level index for model only case

[v-jiaodi]

#3152 (comment)

For model only case we could generate models correctly with proper usage tagged.

@@usage(SAPWidgetService.NonReferencedModel, Usage.input | Usage.output);

model NonReferencedModel {
    @doc("The weight of the widget. This is an int32, but must be greater than zero.")
    prop1: int32;
    @doc("The color of the widget.")
    prop2: string;
}

It would generate the models correctly but the top-level index is not exported. We should include them also for these cases.

/** model interface NonReferencedModel */
export interface NonReferencedModel {
  /** The weight of the widget. This is an int32, but must be greater than zero. */
  prop1: number;
  /** The color of the widget. */
  prop2: string;
}

[MaryGao]

Adjust to p0 task since it has service impact.

[qiaozha]

@kazrael2119 do you see the models being exposed in index.ts when you test for the api subpath issue in models only case?

[kazrael2119]

We noticed there's several automation failures with model only cases

[kazrael2119]

#3222
api view:

index.ts

[MaryGao]

Should be fixed now #3222