tests: use tdd mode, unify karma config, don't depend on puppeteer

Use the same test config for all packages.

Don't depend on the puppeteer and assume chromium is installed to reduce the download size on install.

demo/package.json

@@ -28,12 +28,10 @@
     "glob": "^7.1.6",
     "i18next-scanner": "^2.10.3",
     "karma": "^5.1.0",
-    "karma-chai": "^0.1.0",
     "karma-chrome-launcher": "^3.1.0",
     "karma-firefox-launcher": "^1.3.0",
     "karma-mocha": "^2.0.1",
     "mocha": "^8.0.1",
-    "puppeteer": "^2.0.0",
     "rollup": "^2.18.1",
     "rollup-plugin-consts": "^1.0.2",
     "rollup-plugin-copy": "^3.3.0",