Show correct type of FileTypeIconMap

[LYH977]

As a Typescript Developer, currently there is no way to get all the supported extensions from "FileTypeIconMap.ts" because FileTypeIconMap is{ [key: string]: { extensions?: string[] } }. I cannot even get the key names because the key is set to general type of 'string'

Also, I use IFileTypeIconOptions in my project but the extension is string instead of supported extension literal like 'accdb' | 'archive' | ...

When i try to use keyof typeof FileTypeIconMap, what i get is string | number instead of 'accdb' | 'archive' | ...

Hence, in my project, in order to get all the supported extensions, I would need to copy the whole object of FileTypeIconMap and rewrite the type in my own project. Now FileTypeIconMap is correctly typed(but in my project).

Of course, this is not a good idea because I might miss out new supported extension in future.

Hope FluentUI team could update the type of FileTypeIconMap. Or maybe I can make a pull request.

Thank you.