feat(concatjs): enable junit report for karma_web_test

[kyubisation]

This PR enables junit reports for karma_web_test, by adding karma-junit-reporter as a
dependency and adding an appropriate configuration that works with bazel.

Closes #983

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
  It's unclear to me if this is required or if this is part of base expectation

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature (please, look at the "Scope of the project" section in the README.md file)
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue Number: #983

What is the new behavior?

Junit Report is created at path specified via the XML_OUTPUT_FILE environment variable.

Does this PR introduce a breaking change?

• Yes
• No (I can also refactor this as a breaking change, if adding karma-junit-reporter as a dependency instead of a peer depedency is not acceptable.)

Other information

[alexeagle]

this is great! do you mind rebasing it?

[alexeagle]

I don't think you meant to check in these generated .js files?

[kyubisation]

This might be me misunderstanding the test setup. I compared this with the other .js/.spec.js files in that directory.
Should I have added these tests differently?

[kyubisation]

I should find some time this week to rebase it.
Looking at the current implementation it is a bit awkward to do this without adding karma-junit-reporter as a peer dependency. However that would introduce a breaking change.
What is your opinion on this?

[kyubisation]

Closing in favor of #2630
I noticed that not adding the karma-junit-reporter as a peer dependency causes visibility errors. Due to this, I refactored this as a breaking change in adding karma-junit-reporter as a required peer dependency.
I apologize for not checking/discovering this beforehand. Thourough testing on windows is still not trivial (to me).