Expose line/cursor properties

The current "line" and "cursor" states are often necessary when developing applications that use readline for prompts.

See nodejs/node#30347

types/node/readline.d.ts

@@ -12,6 +12,13 @@ declare module "readline" {
 
     class Interface extends events.EventEmitter {
         readonly terminal: boolean;
+
+        // Need direct access to line/cursor data, for use in external processes
+        // see: https://github.com/nodejs/node/issues/30347
+        /** The current input data */
+        readonly line: string;
+        /** The current cursor position in the input line */
+        readonly cursor: number;
 
         /**
          * NOTE: According to the documentation: