[FEATURE] Generate merged test coverage report

[Rawi01]

Describe the feature
The lombok test workflow should generate a test coverage for all the different enviroments and merge them together into a single coverage report. This is beneficial because running all these tests locally to create a merged coverage report can be time-consuming.

Describe the target audience
Developers working on Lombok who aim to enhance test coverage.

Additional context
Requires some ant and github actions adjustments.