[Bug]: unexpected versioning behavior in http-client-csharp emitter

[jovinson-ms]

Describe the bug

The client emitter respects @added decorators at the property level, but seems to ignore them at the model level.

Reproduction

Given this TypeSpec:

@added(Versions.v2)
model AlsoAddedInV2 {}

model Foo {
  name: string;

  @added(Versions.v2)
  addedInV2: string;
}

running the http-client-csharp emitter with api-version: v1 will output a Foo class without the addedInV2 property, but will also output a AlsoAddedInV2 class.

Checklist

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• The provided reproduction is a minimal reproducible example of the bug.