Replace Things with Clients

[dborovcanin]

Is your feature request related to a problem? Please describe.

No, it is not.

Describe the feature you are requesting, as well as the possible use case(s) for it.

As we shift from IoT to an event-driven architecture platform, we should update our codebase to reflect that. Under the hood, we are already using client concept, we only need to emphasize it through the documentation and terminology we use.

Indicate the importance of this feature to you.

Must-have

Anything else?

No response