Refactor & migrate packages to organization

[lihbr]

Before it becomes too complicated it'll be nice to rename & migrate current packages to prismicio or a new slicemachine (can make more sense I think?) npm organization.

Migration suggestions:

Before	After
next-slicezone	@slicemachine/next-slicezone
vue-slicezone	@slicemachine/nuxt-slicezone 1
nuxt-sm	@slicemachine/nuxt-module or @slicemachine/nuxt
sm-api	@slicemachine/api or @slicemachine/client
sm-commons	@slicemachine/common

¹ Since it currently relies on Nuxt lifecycle it's misleading to have it named "vue", and we'll make a slice zone per meta framework anyway...

[lihbr]

Update 02/17/2021:

1. I'd still love it

[lihbr]

Organization usage ramped up nicely since last year, less packages are being created outside of an org.