Migrate escalation event subprocesses

[berkaycanbc]

Description

Following migration cases will be supported:

(Since escalation event subprocess migration is expected to work the same as error event subprocess migration, I didn't change error start events to escalation ones in screenshots for saving time on documenting the issue.)

Migrate active escalation event subprocess

Mappings should be provided between event subprocesses (sub1 -> sub2) and active elements inside event subprocesses (B -> B).

Migrate escalation event subprocess start event subscription

To migrate the start event subscription of a escalation event subprocess a mapping needs to be provided for active elements (A-> A) and between escalation start events (start1 -> start2). This case currently doesn't provide much advantage since escalation code will not change during the migration, but will be useful when we introduce the feature for re-evaluating escalation codes.

Subscribe to escalation event subprocess start event subscription

In this case, a mapping should be provided for the active element (A -> A). The escalation event subscription will be created after the migration for escalation start event (start2).

Unsubscribe from escalation event subprocess start event subscription

In this case, a mapping should be provided for the active element (A -> A). The escalation event subscription will be deleted after the migration for escalation start event (start1).