Support BPMN Call Activity to call another app process

### Description

Sometimes we need to instantiate another process aka app, complete this process and then return to the calling processes/app and continue the process there.

This should establish a parent/child relationship between the instance of the calling process/app (parent) and the created instance in the called process/app (child).

The user experience should ideally be integrated within the current process the is in working on to allow for a complete process navigation regardless of what "app" you are within rather than being sent out to another app, with another (unrelated) navigation and in the end to return to the calling app process.

### Additional Information
The usage scenarios varies, but two of then are:
* SSB has a evaluation app that they would like to include as a mandatory step in other app's processes before they allow the user to finish the main process.
* BR has a app where the best user experience is achieved by allowing the user to fill out a form "inline" within a tab component within a process step. The main process p

### Tasks

_No response_

### Acceptance Criterias

_No response_

No files, tests, or entry points are named. Start by locating the process-instance and navigation handling in app-lib-dotnet, then clarify how a BPMN Call Activity should create a parent/child process relationship, complete the child, and resume the parent; done requires agreed acceptance criteria for inline navigation and both described usage scenarios.

Written by the indexing model from the issue text.