Add flag --fail-on-uncovered (closes #306)

[hugochinchilla]

Here is a patch to allow failure if uncovered cases are found.

I could not find any test to cover the changes made to the command nor the Context object, if tests are mandatory please explain where should I fit a test for this use-case.

[smoench]

@hugochinchilla Thank you, nice idea!
This might be covered by a functional test. I already started some in https://github.com/sensiolabs-de/deptrac/blob/master/.github/workflows/continuous-integration.yml#L124 maybe there is a better solution this.

Currently internal php classes are also blamed as uncovered. Need to fix this first.

[hugochinchilla]

Currently internal php classes are also blamed as uncovered. Need to fix this first.

For me this is not a stopper as I have defined a layer named Language where I define all the internal classes to keep uncovered cases at zero.

This is an example of what I do:

    -   name: Language
        collectors:
            -   type: className
                regex: ^Exception$
            -   type: className
                regex: ^JsonException$
            -   type: className
                regex: ^Throwable$

[hugochinchilla]

@smoench I have updated the PR to include new logic to not blame php internal classes as uncovered. There are unit tests for this feature.

I still can't make a test for the --fail-on-uncovered flag as I don't know how could a introduce a step in the github actions which is expected to fail to mark the step as succeeded. I could do it by executing a shell script which does the test and expects the exit status to be non-zero but seems unclean to me, if this is ok to you tell me where should I place such script.

[smoench]

@hugochinchilla Thanks for try figuring out how to resolve internal class likes. I think the best idea would to resolve this in an other PR.

I still can't make a test for the --fail-on-uncovered flag as I don't know how could a introduce a step in the github actions which is expected to fail to mark the step as succeeded. I could do it by executing a shell script which does the test and expects the exit status to be non-zero but seems unclean to me, if this is ok to you tell me where should I place such script.

This file could be added in .github/workflows.

[hugochinchilla]

@smoench I have created #310 for the other changes and removed them from this PR.

I have also added the missing test for this feature.

[smoench]

Thank you @hugochinchilla