Use Github Pages for code coverage and docs

[antonagestam]

See draft PR: #257

The preview feature is not yet available:

phantom-types/.github/workflows/docs.yaml

Line 54 in 18a79f6

preview: true

https://github.com/actions/deploy-pages/blob/368bf1aa22b9265440e251b9216520e3f91c2d5b/action.yml#L36-L39

Once it is, will open up to some nice workflows and not having to depend on external services for these things.