[@types/blessed] Allow additional properties for IOptions interface (#40547)

* [@types/blessed] Allow additional properties for `IOptions` interface

This change allows for arbitrary properties to be stored
onto the options object of `Node` instances. This is useful
for extra metadata to be stored onto a node and is accessible
on the `node.options` property.

For example, the `blessed-css` module utilizes the additional
properties `id` and `className` for matching CSS selectors:

```typescript
const bg = blessed.box({
    parent: screen,
    id: 'bg'
});
```

* Add test

* Add to authors

types/blessed/blessed-tests.ts

@@ -53,6 +53,12 @@ screen.key("q", () => screen.destroy());
 
 screen.render();
 
+// Allow for arbitrary extra properties to be stored in `options`
+const extraProps = blessed.box({
+  parent: box1,
+  id: 'box3'
+});
+
 // https://github.com/chjj/blessed/blob/master/test/widget-bigtext.js
 
 screen = blessed.screen({

types/blessed/index.d.ts

@@ -3,6 +3,7 @@
 // Definitions by: Bryn Austin Bellomy <https://github.com/brynbellomy>
 //                 Steve Kellock <https://github.com/skellock>
 //                 Max Brauer <https://github.com/mamachanko>
+//                 Nathan Rajlich <https://github.com/TooTallNate>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 // TypeScript Version: 2.1
 
@@ -595,7 +596,9 @@ export namespace Widgets {
         destroy(): void;
     }
 
-    interface IOptions {}
+    interface IOptions {
+        [name: string]: any;
+    }
 
     interface IHasOptions<T extends IOptions> {
         options: T;