[FIR] Extension point for function calls

This extension point allows changing the return type of call
 from a declared type to its subtype.
With an idea that such a plugin needs the ability to
control available (extension) properties for this type.
A set of properties should be decided based on the resolved function,
provided arguments, types, and resolved lambdas.
It is not a goal to enable plugins to affect resolution in any way.
Types are not intended to have any structured capabilities

In other words.
The goal was to come up with a way to enable a limited form
of an "extensible records" mechanism through plugins.
- It should give enough value for a practical use.
(more info in the ticket).
- It should have minimal effect on the compilation process
This appears to be an extension point that solves this problem.

^KT-65859 Fixed

compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/extensions/FirExtensionRegistrar.kt

@@ -38,6 +38,8 @@ abstract class FirExtensionRegistrar : FirExtensionRegistrarAdapter() {
             FirFunctionTypeKindExtension::class,
             @OptIn(FirExtensionApiInternals::class)
             FirMetadataSerializerPlugin::class,
+            @OptIn(FirExtensionApiInternals::class)
+            FirFunctionCallRefinementExtension::class,
         )
 
         internal val ALLOWED_EXTENSIONS_FOR_LIBRARY_SESSION = listOf(
@@ -122,6 +124,12 @@ abstract class FirExtensionRegistrar : FirExtensionRegistrarAdapter() {
             registerExtension(FirMetadataSerializerPlugin::class, this)
         }
 
+        @FirExtensionApiInternals
+        @JvmName("plusFunctionCallRefinementExtension")
+        operator fun (FirFunctionCallRefinementExtension.Factory).unaryPlus() {
+            registerExtension(FirFunctionCallRefinementExtension::class, this)
+        }
+
         // ------------------ reference methods ------------------
 
         @JvmName("plusStatusTransformerExtension")
@@ -195,6 +203,12 @@ abstract class FirExtensionRegistrar : FirExtensionRegistrarAdapter() {
             FirMetadataSerializerPlugin.Factory { this.invoke(it) }.unaryPlus()
         }
 
+        @FirExtensionApiInternals
+        @JvmName("plusFunctionCallRefinementExtension")
+        operator fun ((FirSession) -> FirFunctionCallRefinementExtension).unaryPlus() {
+            FirFunctionCallRefinementExtension.Factory { this.invoke(it) }.unaryPlus()
+        }
+
         // ------------------ utilities ------------------
 
         @JvmName("bindLeft")