refactor: add scripts to separate unit, e2e tests

ci/dev/test-unit.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+main() {
+  cd "$(dirname "$0")/../.."
+  cd test/unit/test-plugin
+  make -s out/index.js
+  # We must keep jest in a sub-directory. See ../../test/package.json for more
+  # information. We must also run it from the root otherwise coverage will not
+  # include our source files.
+  cd "$OLDPWD"
+  CS_DISABLE_PLUGINS=true ./test/node_modules/.bin/jest "$@"
+}
+
+main "$@"