feat: implement listener to send messages when the user press enter

Author: NickChecan

com.developer.nefarious.zjoule.plugin/resources/views/scripts.js

@@ -164,4 +164,10 @@ function finishLoading() {
 		chatBox.removeChild(loadingIndicator);
 	}
 	unblockInput();
-}
+}
+
+document.addEventListener('keydown', function(event) {
+	if (event.key === 'Enter') {
+		sendMessage();
+	}
+});