[GHC] Batch modify: #14123, #14251, #14873, #14899, #15519, #15768, ...

[GHC]

Batch modification to #14123, #14251, #14873, #14899, #15519, #15768, #4012, #7411, #8228, #9370, #10946, #12178, #13233, #13426, #13576, #13624, #13763, #14013, #14226, #14270, #14980, #15267, #15418, #15455, #15488 by osa1:
milestone to 8.10.1

Comment:
Bumping milestones of some high and highest priority tickets.

-- 
Tickets URL: <http://ghc.haskell.org/trac/ghc/query?id=14123%2C14251%2C14873%2C14899%2C15519%2C15768%2C4012%2C7411%2C8228%2C9370%2C10946%2C12178%2C13233%2C13426%2C13576%2C13624%2C13763%2C14013%2C14226%2C14270%2C14980%2C15267%2C15418%2C15455%2C15488>
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