Add changed lines output to the action

[DriesSchulten]

Hi,

the coverage on actual lines changed is currently available and being output in the comment the action can add to a PR. We'd like to have it output the lines changed percentage as metric as well.

Reasoning for this change: when someone adds a new well tested method in a largely untested class with the current output (files changed percentage coverage) would be still very low making it hard to enforce a pass/fail coverage check (as readme suggests) that we would consider 'fair'. Therefore ideally the 'lines changed percentage' would be available as an output as well.

I've added a change on a fork I made that adds the project.changed.percentage to a new output; would there be interest into making it into a PR?

regards

[svenrienstra]

This will fix https://github.com/Madrapps/jacoco-report/issues/71