Move run script to root.

[squidsoup]

Adding support to the demoservice for monorepos is potentially complex, so as a compromise we'll move run to the root, and selectively point at an individual workspace project. Currently the serve' target in package.jsonwill point to theui` workspace, but later will point to the single-spa root project once that is implemented. This does mean we will not have demos for the legacy maas frontend when it is migrated to this repo, but I think we can live with that given it has never had demos.

QA

Run run from the project root. It should spin up the ui app on http://localhost:8000

[webteam-app]

Starting demo at: https://maas-ui-canonical-web-and-design-pr-9.run.demo.haus/

[anthonydillon]

Could you add a clean target too. This should remove all deps and builds.

[huwshimi]

I've added https://github.com/canonical-web-and-design/MAAS-squad/issues/1236 for adding the clean.

[anthonydillon]

Thanks, LGTM 👍