Add multi Capella project handling

[nathanatstariongroup]

Prerequisites

• I have written a descriptive issue title
• I have verified that I am running the latest version of the DEH-Capella
• I have searched open and closed issues to ensure it has not already been reported

Description

As for now the Capella Adapter doesn't support multiple Capella project open.
Add the possibility to select the target or source model among the open Capella projects

Steps to Reproduce

System Configuration

• Capella version:
• Environment (Operating system, version and so on):
• Java version:
• Additional information: