Remove IOPort#

The following GHC.Exts exports should be removed (no deprecation period):

data IOPort# s a
newIOPort# :: State# s -> (# State# s, IOPort# s o #)
readIOPort# :: IOPort# s o -> State# s -> (# State# s, o #)
writeIOPort# :: IOPort# s o -> o -> State# s -> (# State# s, Int# #)

CLC approval: https://github.com/haskell/core-libraries-committee/issues/213

Draft MR: !8776 (merged)

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