typelevel-nix: dev shells for Scala development

[rossabaker]

I'd like to offer typelevel-nix as a Typelevel project.

• Provides a one-liner for individuals to get a fully working dev shell for modern Scala development. This includes SBT with either a "library JVM" (i.e., 8) or an "application JVM" (i.e., 17), along with sbt and scala-cli.
• Composes so projects can create their own flake to specify optional extensions, alternate JVMs, and a direnv integration.
• Has a Jekyll integration to run sbt-microsites according to your Gemfile without leaving a trace in your system or local gem path.
• Non-nix users can continue to cheerfully ignore it.

If accepted, I will transfer the repo into the Typelevel org.

[ChristopherDavenport]

I approve.

[johnynek]

Ship it!

[tpolecat]

👍

[rossabaker]

Looks like a consensus. I'll transfer it over.