Fix double start when activateAfterLongPress is used (#2628)

## Description

It seems like native iOS recognizers (or at least Pan) don't respect
when their state is changed from outside, which caused a problem with
`.activateAfterLongPress` - before sending event in `Active` state, the
state of the native recognizer is updated to
`UIGestureRecognizerStateBegan`. Despite this, after moving the finger
it tries to change the state to `UIGestureRecognizerStateBegan` once
more, causing weird `Active` -> `Began`, `Began` -> `Active` chain.

This PR adds a simple check to detect the first event and stop
processing in case it happens.

~~One thing that *could* be related is the fact that when the gesture
fails before activation, the gesture stays in the `Began` state until
the finger is lifted. This still needs to be investigated.~~ I think
this is a separate issue.

Fixes
#2620

## Test plan

Tested on the example app.

---------

Co-authored-by: Michał Bert <[email protected]>

apple/RNGestureHandler.m

@@ -240,6 +240,15 @@ - (void)sendEventsInState:(RNGestureHandlerState)state
       return;
     }
 
+    // Recognizers don't respect manually changing their state (that happens when we are activating handler
+    // under custom conditions). If we send a custom event in state ACTIVE and the recognizer will later update its
+    // state, we will end up sending ACTIVE->BEGAN and BEGAN->ACTIVE chain. To prevent this, we simply detect the first
+    // weird state change and stop it (then we don't update _lastState), so the second call ends up without state change
+    // and is fine.
+    if (state == RNGestureHandlerStateBegan && _lastState == RNGestureHandlerStateActive) {
+      return;
+    }
+
     if (state == RNGestureHandlerStateActive) {
       // Generate a unique coalescing-key each time the gesture-handler becomes active. All events will have
       // the same coalescing-key allowing RCTEventDispatcher to coalesce RNGestureHandlerEvents when events are