Add more test filters for :node-test target

The helpers can be similar to the ones in the cljs-test-runner (now in a branch, will be PR-ed soon).

They are definitely useful in shadow because of the all-in-one classpath folder approach:

For instance:

  -n, --namespace SYMBOL                             Symbol indicating a specific namespace to test.
  -r, --namespace-regex REGEX  .*\-test$             Regex for namespaces to test. Only namespaces ending in '-test' are evaluated by default.
  -v, --var SYMBOL                                   Symbol indicating the fully qualified name of a specific test.
  -i, --include SYMBOL                               Run only tests that have this metadata keyword.
  -e, --exclude SYMBOL                               Exclude tests with this metadata keyword.

Start at the :node-test target and compare its test-selection entry points with the cljs-test-runner helpers referenced in the issue. Implement namespace, namespace-regex, var, include, and exclude filtering, then verify that the target selects only the requested tests and preserves the default '-test' namespace behavior.