NIOFileSystem: missing String(contentsOf:maximumSizeAllowed:)

[weissi]

Expected behavior

        let string = try await String(
            contentsOf: "/etc/hosts",
            maximumSizeAllowed: .mebibytes(12)
        )

should work.

Actual behavior

API not available

[ali-ahsan-ali]

Taking a look 👍🏽. Does this need triaging first, as in do the CODEOWNERS need to approve this API should exist?

EDIT: Any pointers on starting. At first I thought we could re-use the same Array API since the result is a ByteBuffer that can then be turned into a String, but I wonder if there is something else that is the intended solution.