Automatically make properties without visibility explicitly public in FIR

[JakeWharton]

With a data class, you declare the type public and all the properties become public even in explicit API mode.

public data class Auth(
  val user: String,
  val token: String,
)

However, change to @Poko and such a thing does not compile.

@Poko
public class Auth(
  val user: String,
  val token: String,
)

You have to explicitly mark each property as public. 😢

Since @Poko competes directly with data, I think it makes sense to try and replicate the behavior of not needing an explicit public.

And unlike data, you can still narrow the visibility of a property and have everything work Just Fine™.