Add onPaste prop on web

[tomekzaw]

Refactor these lines:

react-native-live-markdown/src/MarkdownTextInput.web.tsx

Lines 519 to 532 in fb85ea4

	const originalAddEventListener = EventTarget.prototype.addEventListener;
	EventTarget.prototype.addEventListener = function (eventName, callback) {
	if (eventName === 'paste' && typeof callback === 'function') {
	originalAddEventListener.call(this, eventName, function (event) {
	if (divRef.current && divRef.current.contains(event.target as Node)) {
	// pasting returns styled span elements as event.target instead of the contentEditable div. We want to keep the div as the target
	Object.defineProperty(event, 'target', {writable: false, value: divRef.current});
	}
	callback(event);
	});
	} else {
	originalAddEventListener.call(this, eventName, callback);
	}
	};