K2: Rewrite delegate inference

The main idea is getting rid of stub types and using just type variables
See more detailed description at docs/fir/delegated_property_inference.md

The problem with stub types is that they need really special treatment
in many places, and on the other hand, there are no clear contracts on
how they should work (that regularly leads to bugs like KT-59529)

^KT-61060 Fixed
^KT-61075 Fixed
^KT-61077 Fixed
^KT-59529 Fixed
^KT-61633 Related
^KT-61618 Related
^KT-61740 Related
^KT-59107 Related
^KT-61747 Related
^KT-61077 Related
^KT-61781 Related

docs/fir/builder_inference.md

@@ -2,10 +2,6 @@
 See also: [Kotlin Spec: Builder-style type inference](https://kotlinlang.org/spec/type-inference.html#builder-style-type-inference)
 
 ### Glossary
-#### CS = Constraint system
-An instance of `org.jetbrains.kotlin.resolve.calls.inference.model.NewConstraintSystemImpl`
-#### Call-tree
-A tree of calls, in which constraint systems are joined and solved(completed) together
 #### Postponed type variable
 Type-variable, that was used to build a stub type on, and fixation of which is postponed until the end of lambda analysis.
 Selection of type variables to postpone happens during [Initiation](#initiation) phase