Fix EXC_BAD_ACCESS crash on iOS in `[REAAnimationsManager clearShared…

…TransitionConfigForTag:]` (#5975)

## Summary

Fixes
#5947.
Fixes
#5968.

When `react-native-reanimated` is installed but not used directly,
switching between bottom tabs from `@react-navigation/bottom-tabs` will
result in a `EXC_BAD_ACCESS` crash on iOS.

This PR adds missing mock for `_clearSharedTransitionConfigForTag` as
suggested by @bartlomiejbloniarz.

## Test plan

Try repro from
#5947 (comment)

apple/LayoutReanimation/REAAnimationsManager.m

@@ -94,6 +94,9 @@ - (instancetype)initWithUIManager:(RCTUIManager *)uiManager
     _clearAnimationConfigForTag = ^(NSNumber *tag) {
       // default implementation, this block will be replaced by a setter
     };
+    _clearSharedTransitionConfigForTag = ^(NSNumber *tag) {
+      // default implementation, this block will be replaced by a setter
+    };
 #ifndef NDEBUG
     _checkDuplicateSharedTag = ^(REAUIView *view, NSNumber *viewTag) {
       // default implementation, this block will be replaced by a setter