fix incorrect suggestion for !(a >= b) as i32 == c

[CoCo-Japan-pan]

fixes #12761

The expression !(a >= b) as i32 == c got simplified to a < b as i32 == c, but this is a syntax error.
The result we want is (a < b) as i32 == c.
This is fixed by adding a parenthesis to the suggestion given in check_simplify_not when the boolean expression is casted.

changelog: [nonminimal_bool]: fix incorrect suggestion for !(a >= b) as i32 == c

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[Centri3]

I'd say we should use Sugg::maybe_par in clippy_utils for this. The code is correct for this case, but it's missing other cases (mostly binary ops) where parentheses are required. For example, !(1 >= 2) | true == a also causes the same issue, which the suggested function handles.

[CoCo-Japan-pan]

I wasn't familiar with the clippy_utils::sugg, and I think my code is redundant, but I'll push this for now.
I thought we have to keep the parent expression, so I added a stack, but maybe just applying Sugg::maybe_par to the suggestion in let Some(suggestion) = simplify_not(cx, inner) was sufficient?

[CoCo-Japan-pan]

Given the fact that simplify_not only deals with ExprKind::Binary and ExprKind::MethodCall, I believe the problem occurs only when we simplify ExprKind::Binary, and the expression belongs to ExprKind::Cast or ExprKind::Binary (please let me know if there are more), so I changed the need_parens logic.

[bors]

☔ The latest upstream changes (presumably #13443) made this pull request unmergeable. Please resolve the merge conflicts.