**What**
- Move packages for `next` version of admin to core repo
**Other**
- Since this PR introduces packages that depend on Vite 5, it also introduces @types/node@^20. We have never had a direct dependency on the types package for Node, and as far as I can see that has resulted in us using the types from Node.js@8, as those are a dependency of one of our dependencies. With the introduction of @types/node@^20, two of our packages had TS errors because they were using the NodeJS.Timer type, which was deprecated in Node.js@14. We should add specific @types/node packages to all our packages, but I haven't done so in this PR to keep it as clean as possible.
- Q: @olivermrbl I've added the new packages to the ignore list for changeset, is this enough to prevent them from being published?
**What**
- Bumps `class-variance-authority` to new beta version - `cva@beta`.
- Updates all usages of `cva` to new API.
- Clear up the naming of types in `usePrompt`
**Why**
- A bug in how `class-variance-authority` exported its types mean that we were relying on patching the package to ensure that the correct types made it into the build of our UI package. This was important to ensure intellisense for component variants, such as `<Button size="large" />`. Previously in the UI monorepo, having the patch was enough to ensure that the correct types made it into the build, but that was not the case after we moved the design system to the core repo. The issue with types is fixed in the `@1` version of `cva` which is currently in beta. I have pinpointed the version to the current beta version to ensure stability despite the package currently being in beta.
