Fix child argument types in addView methods

[szydlovsky]

Summary

Fixes #850 and #856.
As stated in the first issue, there seem to be unneeded nullabilities in child arguments for Android PagerViewManager (both paper and fabric). Their existence makes the methods override nothing, which in turn crashes the build.

Test Plan

Run on a fresh android app.

What's required for testing (prerequisites)?

Having anything react-native-pager-view related in the app.

What are the steps to reproduce (after prerequisites)?

You need to create 2 differents apps - one with RN 0.74, the other with RN 0.75 - to make sure we don't lose <0.75 compatibility. Then, after installing dependencies just try building via Android Studio.

Compatibility

OS	Implemented
iOS	not relevant
Android	✅

Checklist

• I have tested this on a device and a simulator
• I added the documentation in README.md
• I updated the typed files (TS and Flow)

[saif-o99]

Someone please accept this PR. its urgent fix

[troZee]

Does it work for RN < 75 and the old arch?

[saif-o99]

there is also addView inside main/PagerViewViewManagerImpl.kt
this this also needs to change?

[szydlovsky]

@troZee checked for RN 0.74.4 on both old and new arch - worked fine. 0.75.1 both arches work as well

[szydlovsky]

and yeah, PagerViewViewManagerImpl.kt might also need some tweaks I believe, but everything builds and works fine without it

[szydlovsky]

@troZee should I also add changes to the Implementation files?

[hengkx]

Thank you very much. When will the version be released