Add automation for code coverage in PRs and pushes

[mkorbel1]

Motivation

Many repos have code coverage metrics provided in two places automatically:

• On the README as a badge, indicating coverage for the repo by the test suite.
• In PRs as an indication of how much coverage there is including the changes of the PR.
  • This can also sometimes include a change in coverage relative to the mainline.

Adding automation around these can have some nice benefits, for example:

• Demonstrate to users how well tested the repository is
• Identify testing gaps in new PRs more easily

It would be nice if ROHD (and related packages) had some automation around this.

Desired solution

An automated coverage run that provides information about coverage in PRs and on the mainline. It would be nice to generate the whole HTML report in a way that is easily inspectable.

Alternatives considered

Some tools (even free ones) exist to do a lot of this, but using another software product integrated into the repository requires jumping through some additional hurdles.

Ideally, we are able to implement this without dependence on a 3rd party service.

Additional details

No response