- because of how the npm scripts were set up, we were running the full
Admin integration tests during the unit tests phase of CI
- this commit renames the majority of `test` to `test:unit` in the
package.json files, and aliases `test` to `test:unit`
- special packages like Admin have no-op'd `test:unit` scripts so we
don't end up running its tests
refs https://github.com/TryGhost/Toolbox/issues/363
- this shared library is standalone, and it used in various places of
Ghost core, so we can pull it out to keep it easier to reason about
- we also use the `html-to-text` dependency in another package but it's
outdated and could now switch to this new package
