Idea: simplify Cobertura plugin by using APIs and features provided by Code Coverage API Plugin.

Idea:

• Cobertura plugin benefits from features we offer in the plugin
• There is no breaking changes
• jeffpearce proposed to implement reporter and deprecate/remove old data model
• Oleg: Migration logic for existing data

Acceptance criteria:

• Transparent to users:
  • cobertura() Pipeline step and Cobertura Build Step start contributing to Code Coverage API data model
  • existing data is compatible or automatically migrated

We need to design this ticket. Open questions:

• How do we implement it? Maybe switches to enable API/UI? Duplicate data in the in-memory model? ...
• Could we simplify the data model somehow
• Which parts of Cobertura plugin do we deprecate?