feat(typescript-estree): private identifiers can only appear on LHS of in expressions

[Josh-Cena]

PR Checklist

• Addresses an existing open issue: fixes AST tightening: PrivateIdentifier can only be LHS of BinaryExpression[operator='in'] #9222
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

[typescript-eslint]

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✅ Successfully ran 28 targets

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• nx test typescript-estree --coverage=false
• nx run-many --target=typecheck --parallel
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• nx test eslint-plugin-internal --coverage=false
• nx test rule-schema-to-typescript-types --coverage=false
• nx test parser --coverage=false
• nx test type-utils --coverage=false
• nx test ast-spec --coverage=false
• nx test utils --coverage=false
• nx test typescript-eslint --coverage=false
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• nx test repo-tools --coverage=false
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[Josh-Cena]

Converting it to draft, because TS is very wack about private identifiers: console.log(#a) is also valid.

[JoshuaKGoldberg]

👋 just checking in @Josh-Cena, is there anything we should do with this?

[JoshuaKGoldberg]

Chatted 1:1, this is blocked on a resolution to microsoft/TypeScript#58754.