Return type should be inferred from calls labels and functions return type

[enzoferey]

As of right now the returned type needs to be typed manually like:

createWatcher<Value>
getBatchedValuesOnce<Value>
useBatchedValues<Value>
useBatchedValuesOnce<Value>

This is error prone because the passed calls can change (the label or returned type does not match anymore), so the library should be able to infer the Value type from the calls labels and functions return type.

Inferring the labels should be straightforward with some TypeScript magic. Inferring the labels' types also requires some TypeScript magic but should be doable.

An alternative solution could be to wrap the calls generators in some glue that defines its types, so everything about a call would be defined where the call is defined and then the function using it would pick up those definitions.