Use record in pairwise()

[Albert221]

Hello!

We have records in Dart now. Let's use them as the pairwise() event type ((T, T) or ({T previous, T current})) instead of the current List<T>. The advantage of this would be that it would always have two values, not a list that could be accessed on an invalid index.

It would be a breaking change though.

[hoc081098]

many Streams and operators (combineLatest, zip, ...)can use record types.
I think we should create another pub lib that supports dart 3.0 instead