Test cases of running targets should iteratively appear as they are processed

### Description of the feature request:

Have bazel java test runner report specific test runs outcomes as they finish (or fail), instead of collecting the output at the end of the run and only then reporting it.

### what underlying problem are you trying to solve with this feature?

We use bazel from intellij, and currently the output of running tests is only displayed when the whole process has finished. This is a regression from running tests directly from intellij, which shows a very friendly UI, and especially important when running integration tests which can be lengthy.

Running with bazel 0.20.0.

Start by reproducing the behavior with the Bazel Java test runner from IntelliJ, using the issue's Bazel 0.20.0 context, and trace how test output is handled. Done means specific test-run outcomes appear as each test finishes or fails instead of being collected until the whole process ends.

Written by the indexing model from the issue text.