copy doc comment to module class in scala 3 (#18)

It seems module classes do not inherit the `docCtx` of the module value,
so is failing the `docannotations` test in mill.


In this PR I correct this by adding the Scaladoc annotation to the
module class when we cook the comment for module values.

Tested in Mill repo with the module inspection task

e.g.
https://github.com/com-lihaoyi/mill/blob/86606fb8534f1cc0938798fd51c7efbbc5846962/integration/feature/docannotations/resources/build.mill

```
$ mill -i inspect core

core(build.mill:67)
    The Core Module Docz!

Inherited Modules: Module, WithZincWorker, BspModule, RunModule, GenIdeaModule, CoursierModule, OfflineSupportModule, SemanticDbJavaModule, JavaModule

Default Task: core.run

Tasks: core.task
```

Also Scala 3 seems to include all transitive interfaces in the class
file, making the inspect more verbose because they will be reported via
reflection

build.sc

@@ -8,7 +8,7 @@ import mill.define.Command
 import mill.resolve.SelectMode
 import mill.resolve.Resolve
 object Settings {
- val version = "0.11.0"
+ val version = "0.11.1"
  val pomOrg = "com.lihaoyi"
  val githubOrg = "com-lihaoyi"
  val githubRepo = "mill-moduledefs"

moduledefs/plugin/src-3/AutoOverridePluginDotty.scala

@@ -49,7 +49,11 @@ class AutoOverridePluginDotty extends StandardPlugin {
  comment <- docCtx.docstring(sym)
  do {
  val text = NamedArg(valueName, Literal(Constant(comment.raw))).withSpan(span)
- sym.addAnnotation(Annotation(ScalaDocAnnot, text, span))
+ val annot = Annotation(ScalaDocAnnot, text, span)
+ sym.addAnnotation(annot)
+ Option.when(sym.isTerm)(sym.moduleClass)
+ .filter(sym => sym.exists && !sym.hasAnnotation(ScalaDocAnnot))
+ .foreach(_.addAnnotation(annot))
  }
  }