FIR: Self types draft

[maxim092001]

Proposal

[mglukhikh]

Some more questionable examples:

• @Self on a local class
• @Self on an object (or anonymous object), on ~~an annotation class~~, on ~~an enum class~~, on an enum entry
• @Self on an interface, or on a fun interface
• different kinds of inheritance (class from self interface, class from self class, local class from self class, local class from self local class)
• @Self around inner classes (inner class inside self class, self inner class inside self class)
• @Self sealed class with inheritors