Provide a code coverage report for the devfile and plugin registries

[ericwill]

Is your task related to a problem? Please describe.

This is the devfile/plugin registry version of #18621.

Describe the solution you'd like

Add a code coverage badge to the repository README, or daily report.

Describe alternatives you've considered

N/A

Additional context

N/A

[sunix]

For the che-plugin-registry: eclipse-che/che-plugin-registry#821

For che-devfile-registry: need to introduce automated test and code coverage for bash scripts: reading https://medium.com/wemake-services/testing-bash-applications-85512e7fe2de looks like https://github.com/bats-core/bats-core is a good candidate.
Discussed during team meeting that we would skip it as things may change for devfile 2.0.

[ericwill]

For che-devfile-registry: need to introduce automated test and code coverage for bash scripts: reading https://medium.com/wemake-services/testing-bash-applications-85512e7fe2de looks like https://github.com/bats-core/bats-core is a good candidate.
Discussed during team meeting that we would skip it as things may change for devfile 2.0.

Let's skip the devfile registry for now.