Lint suggestion: `cfg!(not(...))` vs `!cfg!(...)`

What it does

Essentially, warn on cases that use cfg!(not(...)) instead of !cfg!(...).

Advantage

This could also be combined with other lints so that boolean simplification can be applied to cfgs, meaning that something like cfg(any(not(...), not(...)) could be simplified to !cfg(all(..., ...)).

Drawbacks

Maybe this is too pedantic to be enabled by default. There are also cases where someone might prefer the more verbose version for clarity, and maybe the lint would need to offer both.

Example

if cfg!(not(feature = "optimize_for_size")) {
    // ...
}

Could be written as:

if !cfg!(feature = "optimize_for_size") {
    // ...
}

Future extensions

Perhaps there could be other expansions on this too, like converting all(...) and any(...) into separate cfg! statements:

if cfg!(any(windows, unix)) {
    // ...
}

Could be written as:

if cfg!(windows) || cfg!(unix) {
    // ...
}

No implementation files or tests are named. Start by reviewing the requested cfg!(not(...)) versus !cfg!(...) examples and defining the lint's scope and default status; done means the intended cases are linted with an appropriate suggestion and covered by tests.