Publish package with npm instead of yarn

[sjchmiela]

Fixes #8358

Turns out assets indeed are not supposed to be included in the package.

However, since so far token-list was being published with yarn, it was suffering from a yarn bug, which makes it not handle ignored and unignored files properly if there is a negative expression in package.json#files (there are numerous issues with confused people in Yarn repo, one of them — yarnpkg/yarn#8332).

This pull request proposes changes publishing command from yarn publish to npm publish which in itself isn't a huge change (the effect should be the same), but since we'll be using NPM to pack the tarball files will be properly included/excluded and the resulting package will be 5.6 MB unpacked instead of >200 MB.

Alternative solutions:

• remove negative !**/*.spec.* from package.json#files, leave yarn publish, ship library with tests
• remove negative !**/*.spec.* from package.json#files, leave yarn publish, figure out some other way of ignoring files that Yarn will handle correctly (some mix of .npmignore, #files?)
• publish in a two step process — first pack with NPM, then publish with Yarn (what difference would it make?)