Add selection to TextInputChangeEventData in TypeScript types

The native onChange event was updated to emit selection data (162627a)
and the JS companion (c1f5445) added the corresponding types to the Flow
source (TextInput.flow.js) and the generated ReactNativeApi.d.ts, but it
missed the legacy hand-written TextInput.d.ts. This adds the optional
selection field there so all three type sources agree.

Author: nsbarsukov

packages/react-native/Libraries/Components/TextInput/TextInput.d.ts

@@ -515,6 +515,10 @@ export type TextInputKeyPressEvent =
 export interface TextInputChangeEventData extends TargetedEvent {
   eventCount: number;
   text: string;
+  selection?: {
+    start: number;
+    end: number;
+  };
 }
 
 /**