BOMs in UTF-8 files

This is a continuation of https://github.com/MicrosoftDocs/visualstudio-docs/issues/4901, which doesn't seem to have been properly resolved.

I still see `utf-8-bom` in this article. What is the current status of BOMs in VS? Can it correctly detect UTF-8 without a BOM in all file types? If so, can the documentation be updated to use `utf-8` instead?

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#### Document Details

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* ID: e8c8357d-11a6-6f12-b044-5ff44df65d10
* Version Independent ID: 0c103fd7-5cc4-2726-40f8-d759419ae635
* Content: [.NET code style rule options - .NET](https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/code-style-rule-options?view=vs-2019#feedback)
* Content Source: [docs/fundamentals/code-analysis/code-style-rule-options.md](https://github.com/dotnet/docs/blob/main/docs/fundamentals/code-analysis/code-style-rule-options.md)
* Product: **dotnet-fundamentals**
* GitHub Login: @gewarren
* Microsoft Alias: **gewarren**