https://linear.app/unleash/issue/2-1137/roles-unification-on-the-ui
Root and project roles should be managed in a similar manner, which
means using the same roles route and tab for both.
Additionally, this includes a big revamp to the project roles to align
them more closely with the modern and standardized custom root roles
that were recently developed. They mostly use the same components.
There are still more things we want to improve and unify, but we've left
some of that out of this PR due to PR size concerns.
