feat: add shadcn cli registry

[benlife5]

YextSolutions/pages-visual-editor-starter#164

Usage:
REGISTRY_URL=https://reliably-numerous-kit.pgsdemo.com/components npx shadcn add
HeaderText and BodyText are currently available

[asanehisa]

I think this seems like something users will have to be able to add to their repos if they don't use our starter, in that case, would some basic README / documentation be helpful to explain how to implement ?

[benlife5]

I think this seems like something users will have to be able to add to their repos if they don't use our starter, in that case, would some basic README / documentation be helpful to explain how to implement ?

Yeah, for sure. I think we may want to wait for this to solidify before writing docs thought because it's still experimental

[benlife5]

This PR now has this repo directly powering the registry host at https://www.yext.com/s/4174974/yextsites/151161/branch/116486/deploys/recent

REGISTRY_URL=https://reliably-numerous-kit.pgsdemo.com/components npx shadcn add also lists available components

Going to take a look at init now