Waiters composition

I've been using the library for a while and I noticed that I could simplify my code with something like composing of the waiters. For example, given that I have two waiters `bar` and `baz`, I would like to have `foo` waiter that is waiting if one of `bar` or `baz` is waiting.

#### Motivation

Now, first I was thinking about adding array argument support to `isWaiting` so that I could call `isWaiting(["foo", "bar"])` or a bit more explicit convenience function `isAnyWaiting(["foo", "bar"])`.

But after looking into my code I realized it's not enough. In my case, I have some big component
`Foo` rendering smaller components `Bar` and `Baz` that wait on each other. That works fine with current API. It gets more convoluted when you would like to have some other component `Qux` that doesn't exactly want to know about the lower-level ones but needs to know if `Foo` or any of it's children waits. So currently in `Qux` you would need to write

```js
const isFooWaiting = isWaiting("baz") && isWaiting("baz")
```
That's not ideal because `Qux` needs to know too much about `Foo` internals.

#### Proposal

Create a separate method that will create a new waiter if one of the child waiters is waiting. It could be similar in usage to `createWaitingContext`:

```js
const { compose } = useWait();
const { isWaiting } = compose("Foo", ["Bar", "Baz"])
```
* `Foo` is a waiter, you can check if it's waiting with `isWaiting("Foo")`
* `Foo` is always waiting if `Bar` or `Baz` is waiting.
* the open question is should you be able to manually start and end a composed waiter?

#### Anternative idea

Maybe instead adding a `compose` method, we could compose `Waiter` providers? It's just an idea, I don't know if it's possible or makes sense but provier could have an optional name and be a child of another warapper like this?

```jsx

// ...

```
Then if the inner's `anyWaiting()` is `true`, `foo` is waiting in the outer waiter?
Again, it's just an idea.