* [grunt/build] refactor _build:notice task to not depend on npm
The _build:notice task used to rely on the output of `npm ls` to determine where modules were defined, but the task now just asks `license-checker` to include the `realPath` of the modules it describes in it's output, which is ultimately the same thing but works with `yarn` too.
* [grunt/licenses] convert to use lib/packages/getInstalledPackages()
* [grunt/notice/generate] test generateNoticeText()
* [grunt/licenses] tested assertLicensesValid()
* [npm] remove npm dev dep
* [tasks/lib/packages] do not include kibana in "installed packages"
* [tasks/lib/notice] join all notices with the same separator
(cherry picked from commit 5c04ff65fb)
