[BPMN] Reuse Data Types across the process

The goal is to make Data Types available for being reused across other process' elements.

As an example, it'll be possible to reuse data types between the Process Variables and Task Data I/O:

This way, the data types available will be populated from:

• The existing process definition types (eg: once loading an existing process)
• The custom data types being created during the process authoring
• A "data types provider" service, if present
  • In case of BC, it already exist the service, also data types are actually populated by consuming this service
  • In case of kogito, this service is not yet available, but it must be considered during this task for further integration (see work in progess at KOGITO-1808)

The motivation behind this work is to improve the user experience while doing the process authoring.

 Acceptance criteria (both BC and Kogito)

All Data Types options are the same in all places within one process:

• Global, Process and Case file variables
• Assignments
• Data Objects
• Imports
• Multiple Instance
  When a new custom data type is created the data type is visible on all places (datatype dropdowns) within one process.
  When a new custom data type is edited, the changes apply on all places within one process.

Specific to Business central:
All Data Types options are populated with Data Types within the KIE project the process is located in.
Data types from different projects are not populated in datatype dropdowns.