[BPMN] Open subprocesses in a new editor (BC only)

Goal: Ability to navigate to a subprocess definition by opening it in a new editor.

Users expectations: User should be able to open the sub-process from the open editor without using asset library and manual search.

Spaces: Business Central

In-scope:

• goal: open subprocess in a NEW editor (depends on the channel). For instance, notice parent and child processes will end up on different editors, so no editor's state sharing will be available (undo/redo, copy/paste)
• Way: Navigation to subprocess - By using a toolbox button (eg: a new button just below delete icon, as DMN does)
• single source BPMN/XML file, for each process
• Error handling (file not found, etc)

Out-of-scope:

• always open in edit mode (no read-only)
• user navigation parent <-> child editors
• any process scope / context should be inherited from parent
• any interference between editors expected? should child notify parents at some point

Acceptance criteria

• The feature is targeting only Process Editor in Business Central (kogito channels are excluded from this ticket, see KOGITO-4448).
• During authoring processes, when click on the toolbox button of reusable sub-process, the linked process will be opened as a separate asset.