Do not check for worklets if babel plugin was not used (#4107)

## Description

In some environments babel plugin is not used (e.g. it can be omitted
when using `Next.js`). Our detector checks if callbacks are `worklets`
by checking `__workletHash` field. However, if plugin wasn't used, this
will be `undefined`. In that case, our warning will wrongly suggest to
use `runOnJS`. This may be misleading, if plugin was skipped on `web`,
but used on native platforms.

In this PR, we check if plugin was applied by checking empty worklet
function. If it has `__workletHash` field it means that plugin was used.
If it wasn't, we won't suggest using `runOnJS`.

## Test plan

Confirmed by the original reporter

Author: m-bert

packages/react-native-gesture-handler/src/handlers/gestures/GestureDetector/utils.ts

@@ -36,6 +36,16 @@ export const ALLOWED_PROPS = [
   ...nativeViewGestureHandlerProps,
 ];
 
+// In some environments (e.g. `Next.js`) Reanimated Babel plugin might not be used.
+// In that case we would wrongly suggest to add `runOnJS` to gesture configuration, even if the user doesn't use worklets at all.
+// To prevent this, we check whether the plugin is enabled by defining a worklet and checking if the `__workletHash` property is available.
+function emptyWorklet() {
+  'worklet';
+}
+
+// @ts-expect-error if `emptyWorklet` is a worklet, `__workletHash` will be available, if not then the check will return false.
+const wasBabelPluginEnabled = emptyWorklet.__workletHash !== undefined;
+
 function convertToHandlerTag(ref: GestureRef): number {
   if (typeof ref === 'number') {
     return ref;
@@ -105,7 +115,7 @@ export function checkGestureCallbacksForWorklets(gesture: GestureType) {
   const areAllNotWorklets = !areSomeWorklets && areSomeNotWorklets;
   // If none of the callbacks are worklets and the gesture is not explicitly marked with
   // `.runOnJS(true)` show a warning
-  if (areAllNotWorklets && !isTestEnv()) {
+  if (areAllNotWorklets && wasBabelPluginEnabled && !isTestEnv()) {
     console.warn(
       tagMessage(
         `None of the callbacks in the gesture are worklets. If you wish to run them on the JS thread use '.runOnJS(true)' modifier on the gesture to make this explicit. Otherwise, mark the callbacks as 'worklet' to run them on the UI thread.`