Upgrade dependencies; Replace Webpack with Parcel; Replace Puppeteer with Playwright

[alexeyraspopov]

Rationale

I continue working on modernizing the stack and making infra improvements. This PR attempts to upgrade most of dev dependencies or replace some with tooling that doesn't require much configuration and more flexible.

Details

• https://github.com/nteract/semiotic/commit/e44111672a1cc605271fbc53c2bef71648cc1150 Webpack has been used to run local dev docs and it required a lot of dependencies and scripts to do so. I simply installed Parcel (https://parceljs.org), did yarn parcel serve public/index.html (with slight index.html modifications e.g. explicit script tag) and it just worked. The rest of the story is just removing unnecessary dependencies and scripts.
• https://github.com/nteract/semiotic/commit/5a5e0c727c746646ad02ce7a2b46076e9dfa656b Jest dependencies have been upgraded and since Parcel doesn't need explicit Babel config it would be better to separate Jest-related Babel config from the rest
• https://github.com/nteract/semiotic/commit/6181028090aa4080157ce67669f4a3a230f870a6 Previously Puppeteer was used to run a quick script to make a screenshot of a page that uses prebuilt Semiotic sources. Puppeteer was running a local file which may not have access to some files so it would be better if something served the target file. Something like Parcel that we now have. So I thought for a second what it would take to update Puppeteer config to run Parcel server before making screenshot and then I figured it would be just easier to replace it with Playwright (https://playwright.dev) that not only does it seamlessly, but provides waaaay more abilities with regard to integration testing. Thus, I made a quick integration test that creates a screenshot as a result. Feeding two birds with one scone.
• https://github.com/nteract/semiotic/commit/497431c8c61104237bdfffc3e76edb5683807afe These are the files that I haven't found used anywhere, so cleaning up
• https://github.com/nteract/semiotic/commit/051d1ce5be731676d613fc02a35c57bb196023b7 The build started failing due to TypeScript arguing about this line. I will make sure we catch these type of errors earlier

[willingc]

Ignoring Travis build failure since we are moving away from it.