Comments for all types and ensure comments are generated too

[matt2e]

We have our template to generate the file here: go-runtime/compile/external-module-template/_ftl/go/modules/{{ range .NonMainModules }}{{ push .Name . }}{{ end }}/external_module.go

For verbs, we include comments like this:

{{- else if is "Verb" . -}}
{{.Comments|comment }}
{{if .Comments}}//
{{end -}}
//ftl:verb

We do not do this for any other declaration (enum & typealias)