feat: handle rune

[nythrox]

#790

Usage:

const value = Rune.constant(0 as number | string)

// match by class
value.handle(String, (num) => Number(num))
// match by predicate
value.handle((num): str is String => typeof num ==  "string", (num) => Number(num))
// match by value
value.handle("", () => undefined)

possible changes:

• change name of RunMatch (RunHandle is already taken, maybe refactor)
• handleError function

[nythrox]

Some thoughts:

• the alt parameter in handle() could receive T instead of ValueRune<T, never>. I think T is easier to use, but ValueRune encourages serializable code (should we treat this differently for lib devs x end users?)

• a handleError would allow you to do the same thing, but on the U channel

• having a Rune.error() would allow us to type errors (!) and easily handle/rehandle values. You could use this in chain, filter, etc. to change the channels of a value/error, handle/transform it, etc