fix: rename setScrollEnabled to setScrollEnabledImperatively on old arch

[okwasniewski]

Summary

Rename setScrollEnabled to setScrollEnabledImperatively to fix setting scroll enabled by calling a method on ViewPager ref.

Currently when calling ref.current?.setScrollEnabled(false); we get this error message:

This was left over from the new arch migration. Fixes: #750

Currently when

Test Plan

Render this button in basic example and check if it works.

<Button
                  title="Set scroll enabled imperatively"
                  onPress={() => {
                    ref.current?.setScrollEnabled(false);
                  }}
                />

Compatibility

OS	Implemented
iOS	✅
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)