Suppress sorbet type errors when using `undef'

[dduugg]

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Per discussion on #17998 this unblocks us from strict typing OS extensions (and a few other places), perhaps pending a re-architecture of how we approach such extensions.

I've also included a fix for #18008 (comment) and included the output of brew tc --update --suggest-typed

See https://sorbet.org/docs/error-reference#3008

[Bo98]

Makes sense to me.

The problem the error is flagging isn't really a problem if we're always redefining the method again afterwards - it's simply telling us that Sorbet ignores undef which is OK as it's only there as a warning silencer.

Redefining is covered under 4010 which I assume works correctly given Sorbet ignores undef. In fact, Sorbet ignoring undef is in turn very useful for that reason.

[MikeMcQuaid]

Nice, looks good, thanks @dduugg!