Review `core-electron` and `core-mobile` dependency on `presentation-common`

[grigasp]

At the moment both core-electron and core-mobile have a dependency on presentation-common, because they automatically register the PresentationRpcInterface. I think that should be reconsidered, because:

• PresentationRpcInterface is not registered in case of web RPC, so there might be confusion why some hosts do that automatically others don't. And the web RPC can't automatically register PresentationRpcInterface because of circular dependencies between core-backend and presentation-backend.

• There may be applications that don't need a Presentation RPC, e.g. imodel-console. In that case we have those dependencies unnecessarily.

4.0 seems like a good time to make the change.

[calebmshafer]

I agree, we should be consistent with the way we handle this going forward and it should have minimal impact overall. Let's try to get this in this week for the 4.0 release.

We'll need to make sure to update the Mobile SDK (@tcobbs-bentley and @toddsouthenbentley) as well as the iTwin Viewer desktop app (@aruniverse @ben-polinsky).

[tcobbs-bentley]

@calebmshafer The SDK portion of iTwin Mobile SDK does not contain any backend code. The iTwin Mobile sample app does. So the sample app will need to update to register this RPC, which should be easy.