managedNonce should handle the async cipers from webcrypto

if I do 

```ts
import { gcm, managedNonce } from '@noble/ciphers/webcrypto'
```

and then try to use managedNonce with
```ts
const aes = managedNonce(gcm)(key)
```

I get an error because managedNonce expects synchronous functions only.

May we get a version that handles async functions as well ?

Thank you for writing these libraries - they are a great help to all.