[ext-preview] Inline @babel/generator

Turns out we were only using this in PrintHIR and in the logger, so it should be safe to inline and makes installing the plugin for external collaborators a little easier. I'm assuming inlining this is ok because we only need to defer to the host's Babel version(s) when it affects parsing or the final codegen output, hence why we continue to no-inline @babel/types – as it is responsible for creating AST nodes during codegen