feature request: option to choose formatter for the same filetype

[swann-castel]

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Describe the feature

I've added this config in formatters_by_ft = { typescript = { "biome-check", "prettierd" } } with stop_after_first = true in default_format_opts.

I would like something to trigger biome formatting only when biome.json is found, same for prettier with a .prettierrc file.

My use case is that I have several projects, some already migrated to biome, some still using prettier.

Provide background

No response

What is the significance of this feature?

strongly desired

Additional details

No response