Add a CI job that automatically publishes previews of the Sway Book, Reference and std docs for PRs

Currently, when opening PRs for docs, we need to either host them ourselves ([like this](https://github.com/FuelLabs/sway/pull/3937#issuecomment-1409844890)) or expect maintainers to clone the branch and manually build all of the docs themselves to check things like rendering, linking, and so on.

It would be great if we could have a job that runs on each PR commit, publishes a preview of all docs to some preview URL and provides a link. These preview docs could be safely deleted upon closing/merging the PR into `master`.

I remember netlify having some handy GitHub action that does something like this for previewing website builds before you merge them into master. Would be super handy to have something like this.

I expect this would be useful for all repos that host docs, i.e. `sway`, `fuels-rs`, `fuelup`, `fuel-docs`, etc.

Start by reviewing how the Sway Book, Reference, and std docs are built, then compare GitHub Actions and Netlify-style PR preview options. The completed work should build all three docs for each PR commit, publish a preview URL in the PR, and remove the preview when the PR is closed or merged into master.

Written by the indexing model from the issue text.