Add calculated Content-Type header in HTTPResponse

Need add calculated Content-Type header in HTTPResponse because if need add Content-Type in response then need add it into swiftopenapi.yaml file, but it it is to many options of Content-Type header. On image exist only some of many

Start by reading HTTPResponse and the referenced swiftopenapi.yaml to understand how response headers and Content-Type options are currently represented. Clarify how the header should be calculated across response bodies, then confirm that the resulting behavior covers the requested image case and the supported content types.

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