[TCGC] a helper function to show whether a type is wrapped by `HttpPart`

For the property `temperature`, TCGC emits its type to a model. The model contains properties for `body` and `contentType`. Emitters may only care about type of `body`. Then how to judge whether we need to parse the property type specially?

```
op float(
@header contentType: "multipart/form-data",
@multipartBody body: {
temperature: HttpPart<{
@body body: float64;
@header contentType: "text/plain";
}>;
},
): NoContentResponse;
```

One solution is that judge its `kind` like [here](https://github.com/Azure/autorest.python/pull/2815/commits/574ec8dacb91c1210d95fafff95e30da7511f048#diff-97e08823c94cd89b94201c510751899a6390cc43cde84849e1d744f63bf6527c). However, it is not that robust. Since common body may could also define property with `prop: {@body body: string}` like [here](https://cadlplayground.z22.web.core.windows.net/cadl-azure/?c=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%2BYAh3MgyFNzIChwcm90b2NvbCBhbmQgaG9zdG5hbWUsIGZvciBleGFtcGxlOgrpAPRlc3R1cy5hcGku8gD%2FKS4KICovxX7IXzogc3RyaW5n5ACYfeQBCOcCvGVkKOcAvy7mAJrnAP3oAmpzKQrkAIZzcGFjZSDVKjsKCuQA41RoySDvAUgg5wFzIMdzLuQAnGVudW0gyGTlASrERccRIDIwMjItMDgtMzHELCAg5AK%2FRGVwZW5kZW5jeSjrAuLIQy52MV8wX1ByZXZpZXdfMikKICBgyUYwYCwKfQoKb3AgYWPkAogoYm9keTrFdkDECyDKEM4SZmxvYXQzMuUBNH0pOiB2b2lkOwo%3D&e=%40azure-tools%2Ftypespec-autorest&options=%7B%22linterRuleSet%22%3A%7B%22extends%22%3A%5B%22%40azure-tools%2Ftypespec-azure-rulesets%2Fdata-plane%22%5D%7D%7D).

So maybe TCGC need provide a helper funcion (e.g. `isWrappedByHttpPart` to help emitters judge whether need special logic for the property type.