BEF: Bazel TEST_XYZ environment variables are not populated by Eclipse JUnit test launcher

[plaird]

When running tests from the command line, we can rely on a suite of TEST_ environment variables to be set.

https://bazel.build/reference/test-encyclopedia#initial-conditions

These are not set when the tests are run with the Eclipse launcher. We should find a way to set all of them, but especially TEST_SRCDIR and TEST_TMPDIR since those are required.

For reference, equivalent issue from the IJ plugin: bazelbuild/intellij#193