Support sub process mapping in instance migration mode

[pedesen]

Description

Zeebe will support migration of process instances with sub processes.
Operate needs to enable users to map sub processes in instance migration mode.

User Story

Scenario: As an Operate user
    Given I am in instance migration mode (mapping step)
    When I select a sub processes as source element
    Then I can select a sub process as target element

Acceptance Criteria

• Sub processes are available in the list of source elements
• Sub processes are selectable in the source diagram
• Source sub processes are mappable to target sub processes
• Source sub processes can only be mapped to sub processes

Out of scope

Event sub processes and changing of scope are currently not supported in Zeebe (see #15923). In Operate this will not be respected, which means mapping event sub processes and changing of scope will be possible, and end in a rejection by Zeebe.

Definition of Ready - Checklist

• The issue has a meaningful title, description, and testable acceptance criteria
• If documentation needs to be updated, an issue is created in the camunda-docs repo, and the issue is added to our Operate project board.
• If HELM charts need to be updated, an issue is created in the camunda-platform-heml repo, and the issue is added to our Operate project board.
• Potential Security risks have been considered and added to the product-hub issue risk assessment
• Cross-team dependencies have been considered

Optional:

• Design input has been collected by the assignee

👉 Handover Dev to QA

• Handy resources:
  BPMN/DMN models, plugins, scripts, REST API endpoints + example payload, etc :
• Example projects:

• Versions to validate:

Docker file : in case that it needed to be tested via docker share the version contain the fixed along with version of other services .

• Release version ( in which version this fixed/feature will be released)

📗 Link to the test case