Document removal of IrDeserializer.IrLinkerExtension and related classes in API changes (#1430)

* Document removal of IrDeserializer.IrLinkerExtension and related classes in API changes

See the commit which removed this:
JetBrains/kotlin@c2122db#diff-7083caf53f53703e1d1c65d198007306455dfa5878601b206c35cb2ba6512cfd

In general, this incompatibility change should not be triggered anywhere, unless someone tries to call the missing `IrDeserializer.IrLinkerExtension.resolveSymbol` by hand. We do not see any such External Usages

* Update reference_guide/api_changes_list_2025.md

Co-authored-by: Karol Lewandowski <karol86@gmail.com>

* Update reference_guide/api_changes_list_2025.md

---------

Co-authored-by: Karol Lewandowski <karol86@gmail.com>

Author: fedochet

reference_guide/api_changes_list_2025.md

@@ -87,3 +87,9 @@ Coroutines running under `Dispatchers.Main` do not hold the write-intent lock
 
 `org.jetbrains.kotlin.KtFakeSourceElement` class renamed to `org.jetbrains.kotlin.KtFakePsiSourceElement`
 : Update code usages.
+
+`org.jetbrains.kotlin.ir.linkage.IrDeserializer.IrLinkerExtension` class removed
+: This class was removed from the Kotlin compiler and is no longer available.
+
+`org.jetbrains.kotlin.ir.builders.TranslationPluginContext` class removed
+: This class was removed from the Kotlin compiler and is no longer available.