Finish integrating website and cypress into RushJS

[spencercorwin]

Description

We still need to run rush prune-node-modules and rush link-root before building the website for it to work properly (in dev and prod mode both). We should be able to remove the need to run rush link-root by making sure React Static and Cypress both know where to find node_modules. It actually works for React Static in dev mode, as of #2109, but not prod mode. rush prune-node-modules will always be necessary to be sure that we're building the website with the latest source code (from dist) and not from @neo-one packages that are pulled from NPM for @neotracker/core.

Ideally we should also integrate the neo-one/cypress folder into packages. Probably in neo-one-build-tests or neo-one-build-tools-web. That folder was never migrated post-RushJS