Refine access control support

[vasa-develop]

IpfsDB uses OrbitDB at its core, which uses AccessController class by default, for access control. It also allows you to extend the AccessController class, allowing you access control using anything ranging from authenticating with Metmask, DIDs, etc., to calling any APIs to validate access.

Currently, we have following in our mind:

• IpfsDB will have 1 default access control, which will be extended from the AccessController class. The design goal for this default access control is to provide interoperability across multiple contexts.
  For that, we're thinking to introduce access control using multiple DIDs by default, but it's still an ongoing discussion.

• Apart from a default access control, IpfsDB also provides several pre-implemented access control models that suit specific use-cases. We're open to discussing possible use-cases and access control models.

• Also, at last, we will also expose the OrbitDB's access controller implementation, so that you can still extend it, in cases that are not covered with the provided access controller options.

So, the aim here is to keep and extend the OrbitDB AC model, provide some interoperable ACs out-of-the-box, and also expose the same OrbitDB AC implementation, so that you don't lose the flexibility.

Feel free to add your suggestions, concerns, etc. Go crazy!