Function namespaceId

namespaceId(providerId: string, innerId: string): string
Prefix a provider-local id with its provider id so it is unique across the composite.
Parameters
- providerId: string
  The provider that owns innerId.
- innerId: string
  The id as the provider knows it. May itself contain :.
Returns string
"<providerId>:<innerId>".
Example
```
namespaceId('private', 'direct:ab,cd'); // 'private:direct:ab,cd'
```