chore: check less stuff into node_modules

We bundle our deps, but we don't need to bundle docs, changelogs,
editorconfigs, test coverage reports, .github workflow definitions,
lint configurations, and all the rest, which we never use.

This cuts about 10% off of our publish artifact file size.

```
$ ls -laF npm-7.16.0-*.tgz
-rw-r--r--  1 isaacs  staff  7174497 Jun  3 13:01 npm-7.16.0-release-next.tgz
-rw-r--r--  1 isaacs  staff  6782377 Jun  3 13:00 npm-7.16.0-trim-node-modules.tgz

$ ls -laF npm-7.16.0-*.tar
-rw-r--r--  1 isaacs  staff  19020288 Jun  3 13:01 npm-7.16.0-release-next.tar
-rw-r--r--  1 isaacs  staff  17474048 Jun  3 13:00 npm-7.16.0-trim-node-modules.tar
```

Author: isaacs