Add react-router-monorepo template

[gabro]

I find myself often wasting a bunch of time setting up a Bento monorepo, so I figured we could use some template mechanism.
I've kept it extremely simple, no fancy template generators/scaffolding, just a directory we can clone using a tool like degit

The workflow is then:

pnpx degit buildo/bento-design-system/templates/react-router-monorepo my-new-project
cd my-new-project
pnpm install
pnpm dev

and you're good to go.

We can add as many templates as we like, at the moment I've chosen RRv7, since it's the one I'm betting on for future projects.

The only other minor thing I've added to this PR is to automatically update the Bento version in the template when we release a new one.