Fix optional Content-Type header detection by unifying parameter processing

[Copilot]

• Understand the issue: The previous fix in PR Fix optional Content-Type headers being transformed to enums (emitter-only) #9495 added Content-Type header detection in type-converter.ts, but it relies on sdkProperty being passed to fromSdkType. The fromHeaderParameter function in operation-converter.ts doesn't pass the header parameter to fromSdkType, so the fix doesn't work.
• Fix fromHeaderParameter to pass the header parameter p to fromSdkType so the Content-Type detection can work
• Unify all parameter-processing functions to pass property instance to fromSdkType:
  • fromQueryParameter
  • fromPathParameter
  • fromHeaderParameter
  • fromBodyParameter
  • updateMethodParameter
• Investigated making sdkProperty required - not feasible as many callers have no property context (model base types, array/dict value types, etc.)
• Run existing tests to verify the fix works (all 177 tests pass)
• Fix CI formatting issues
• Run code review and security checks

Original prompt

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This section details on the original issue you should resolve

<issue_title>Fix optional contentType issue</issue_title>
<issue_description>As described in Azure/azure-sdk-for-net#55300, but the issue belongs in this repo.</issue_description>

<agent_instructions>The previous fix does not really fix the issue entirely.
Please fix this again following the root cause in this comment: #9494 (comment)</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@ArcturusZhang I think this is not fixed. The fix introduced an extra check to see if it is a content type header, by checking if the `sdkProperty` is not undefined, but in our code, when the `fromSdkType` is called converting the method parameters (for instance [here](https://github.com/microsoft/typespec/blob/f1a7649b3b53ab7d30488cf7274f813696cdf2d0/packages/http-client-csharp/emitter/src/lib/operation-converter.ts#L482)), the `sdkProperty` argument is never passed in. Therefore the fix is not actually running.

• Fixes Fix optional contentType issue #9494

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[ArcturusZhang]

@copilot please fix the CI issues.

[Copilot]

@copilot please fix the CI issues.

Fixed the formatting issue in 43ba7df. The CI was failing because of a long line that needed to be broken into multiple lines.