Namespace the APIs

[AuHau]

This is maybe related to general API design discussion for BeeJS, but I feel like that the API surface of Bee class is growing a lot and maybe introducing namespacing would introduce more clear structure.

Just an example:

const bee = new Bee(...)

bee.collection.upload()
bee.feed.upload()
bee.feed.createWriter()

But I guess this depends on what path we decide to go with BeeJS

[vojtechsimetka]

There is also a request to expose the Utils directly on the bee instance which would be much easier with the proposed namespacing.