Applying multiple formatters in sequence

From the documentation I see that `formatFiletypes` can take an array of formatters for each file type, but from a very cursory reading of the code it seems like they are run async.

My use case is that I would like to run Prettier, and only then ESLint (kind of like [prettier-eslint](https://github.com/prettier/prettier-eslint-cli) does, but without using it.

Is something like that possible?

Start by comparing the documentation for formatFiletypes with the formatter implementation, focusing on how an array of formatters is scheduled. Check whether Prettier followed by ESLint is supported, and define completion as a confirmed sequential behavior or a clearly documented limitation.

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