Update all Transducer reducer signatures to include indexOrKey and fold

Update reducerMap, reducerFilter, reducerFlatMap, reducerForEach, reducerTryCatch

Update all instances of Reducer and Transducer in docs to this

```
* type Reducer = (
* accumulator any,
* value any,
* indexOrKey number|string|any,
* fold Foldable
* )=>(nextAccumulator Promise|any)
*
* type Transducer = Reducer=>Reducer

```