Add test coverage report/badges

[collado-mike]

Is your feature request related to a problem? Please describe.

We should publish badges for the state of the build

Describe the solution you'd like
Badges on the front page of the repo

[snazy]

@collado-mike there's a badge in #180 for the state of CI.
Not sure whether this issue is about the badge or test-coverage (aka jacoco)?

[MonkeyCanCode]

@snazy / @collado-mike as we have other workflows as well, should we add those status as well (or create a main workflow then links those to that then get status from main workflow instead?)