[test]: e2e tests

[bennypowers]

#36 installs some seemingly useless devDependencies:

    "@open-wc/testing": "^2.5.33",
    "@rollup/plugin-babel": "^5.3.0",
    "@web/rollup-plugin-html": "^1.9.1",
    "@web/rollup-plugin-import-meta-assets": "^1.0.7",

and

    "lit": "^2.0.0-rc.2",

These are here because our integration testing writes actual files to the /create package root, therefore eslint import plugin is able to resolve them in /create/node_modules. This is not ideal. Tests which rely on the scaffolded package's node_modules should run e2e in an isolated temp dir that's not affected by create's node_modules, or in a virtual filesystem where deps are stubbed.

Originally posted by @bennypowers in #36 (comment)