Improve JPA View entity definitions

[zambrovski]

Scenario

• camunda-bpm-taskpool version: 3.13
• Camunda BPM version: 7.18
• Description of your use case: The entity definitions should be improved.

Current Behaviour

Currently only few field annotations exists on task, data_entry, process_definition.

Wanted Behaviour

Columns sizes and indexes should be present in entity code, so e.g. generated SQL code is more accurate.

Possible Workarounds

Manually change SQL.