`no-implicit-coercion`: allow `!!` operator for improved control flow analysis

See release notes for TypeScript 4.4: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-4.html#control-flow-analysis-of-aliased-conditions-and-discriminants See demo: https://www.typescriptlang.org/play?#code/CYUwxgNghgTiAEYD2A7AzgF3gDwFz0xgEsUBzeAH3hQFcIIBuAWAChXl0sAjJJCEKCgDCqYEQxFU8ALzwAQr36CAFNgCUrVkQBm8ZTz4Dho8ZJRr4Ab1bxb8APT34IGDCQx4ACxcgbdjmiGAHQQSKSqQRhIADJIAO4uQlBoIMpqGiwAvposAVgADjRwIihiElKyAISV2Dk6eoXFJuXmVn62jvBcNFgoSM6u7l4+7YiogfwhYRFRsQkwSSlpGZlAA