Fix memory leak in TextInput

[mobinni]

Summary:

When implementing a local FPS monitor I noticed that TextInput leaked memory. @tomekzaw helped triage and confirm whether the leak was occurring in reanimated or react-native upstream.

We collaborated on a fix for this and noticed that this was fixed 6 years ago in text here

We've ported the same fix to BaseTextInputShadowNode.h

Changelog:

[General] [Fixed] - Fix memory leak in TextInput

Test Plan:

https://snack.expo.dev/@mobinni/memory-leak-reproducer

• Run this with XCode instruments and see memory grow over time

[tomekzaw]

Fixes software-mansion/react-native-reanimated#7647 as well.

[javache]

Thanks! We should really use a different data structure than ShadowView in AttributedString...

[meta-codesync]

@javache has imported this pull request. If you are a Meta employee, you can view this in D94267721.

[react-native-bot]

This pull request was successfully merged by @mobinni in 5229e50

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