Update CommentRule.lineComment to support LineCommentConfig

[amyssnippet]

fixes #290146

As of VS Code 1.91 (via #243283), the lineComment property in CommentRule can be an object (LineCommentConfig) in addition to a string. This PR updates the interface to string | LineCommentConfig to match the runtime behavior and prevent type errors for consumers.

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[RedCMD]

• vscode-dts: Add LineCommentConfig interface & update lineComment #289457