fix: NSNull treatment

[Tiagoperes]

Problem solved

When running Nimbus Core on iOS, every property in a Map or Array that was null on Kotlin will be NSNull on Swift. For this reason, we must check for NSNull in some situations instead of just checking for null.

In most of the scenarios where we need to get a value from the property map we also use the class AnyServerDrivenData. To fix the issue, I made AnyServerDrivenData aware of NSNull, making it treat NSNull just like null.

New usages for AnyServerDrivenData

The operations were not using AnyServerDrivenData and where it made sense I replaced the direct accesses with it. Where it didn't make sense, I made sure NSNull was being accounted for.

I also replaced valueOf in the component forEach.

Also fixed

• It was possible to get IndexOutOfBounds in many of the operations if the arguments were passed wrong. I fixed it with a proper error message.
• This problem was observed when we attempted to use navigation params. Although it ended up not being the actual problem, I created a simple test to validate this feature.