Replace Python yamllint with NPM yaml-lint

Most of the linters are in Node, so changing yamllint with Node version simplifies local testing.

Downside: I don't know what feature-parity is between the linters.

```shell
$ npm install yaml-lint
$ npx yamllint '**/*.yaml' --ignore='node_modules/**'
✔ YAML Lint successful.
```
(Note: this depends on #2323)