First-class support for "alternative" toolkits

[armanbilge]

Is your feature request related to a problem? Please describe.

Inspired by the Scala Toolkit, we have created a Typelevel Toolkit. cc @TonioGela

Describe the solution you'd like

//> using toolkit "typelevel:latest"

Or something similarly simple e.g.:

//> using kit "typelevel:latest"

Describe alternatives you've considered

Currently we are doing:

//> using lib "org.typelevel::toolkit::0.0.3"

[tgodzik]

I think probably //> using toolkit "typelevel:latest" would be best. It shouldn't add too much on top of the main toolkit.