Fixes an issue in openJsDocLink command due to incorrect typings in OpenJsDocLinkCommand_Args.

The openJsDocLink command currently declares the type of its args parameter as

{
        readonly file: vscode.Uri;
        readonly position: vscode.Position;
}

However, the type of the actual argument given to the command is

{
        readonly file: UriComponents;
        readonly position: { line: number; character: number; };
}

As a consequence, while the command does convert args.file to vscode.Uri via vscode.Uri.from(args.file), it misses converting args.position to vscode.Position. This works by accident in VS Code, but causes an issue in Eclipse Theia (eclipse-theia/theia#13568).

This PR fixes the typings in OpenJsDocLinkCommand_Args and adds the necessary conversion for args.position.