Support vals in @Id annotations when compiled under scaladoc

[neko-kai]

Issue described in https://t.me/izumi_ru/3971

[info] Main Scala API documentation to /home/circleci/project/target/scala-2.13/api...
[error] /home/circleci/project/src/main/scala/com/ponv/Scenarios.scala:16:26: exception during macro expansion: 
[error] izumi.distage.model.exceptions.BadIdAnnotationException: Wrong annotation value, only constants are supported. Got: @izumi.distage.model.definition.Id(izumi.distage.model.definition.Id(com.ponv.Loggers.Welcome))
[error]  at izumi.distage.reflection.ReflectionProviderDefaultImpl.withIdKeyFromAnnotation(ReflectionProviderDefaultImpl.scala:34)

BadIdAnnotation is thrown in scaladoc mode during compilation with the following construct:

final val X = "x"

new ModuleDef {
  make[Any].from { d: Dep1 @Id(X) => ??? }
}

This happens because normally @Id(X) would be expanded to @Id("x") before the macro is called, however, this does not happen in scaladoc mode, because scaladoc erases literal singleton types for the purpose of showing widened String type in the documentation, this causes X to not be inlined. (this was already discussed in this tracker before somewhere and this was the response to the bug in the scala tracker)

We should somehow detect that we're running under scaladoc in FunctoidMacro and NOT throw the error in that case. We may possibly be able to detect it by checking for empty positions in c.enclosingPosition / or .pos methods on trees – normal mode always has good positions, but scaladoc mode often has empty broken positions – but there may be better ways to detect scaladoc too.