[Clang] Support MSPropertyRefExpr as placement arg to new-expression (#75883)

It seems we were forgetting to call `checkArgsForPlaceholders` on the
placement arguments of new-expressions in Sema. I don't think that was
intended—at least doing so doesn't seem to break anything—so this pr
adds that.

This also fixes #65053

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Co-authored-by: Erich Keane <ekeane@nvidia.com>