[FIR2IR] Automatically store IR declaration in its parent upon creation

Previously, creating a declaration with Fir2IrCallableDeclarationsGenerator/
  Fir2IrClassifiersGenerator didn't guarantee that this declaration will
  be actually added to the list of parent class/file declarations, which
  lead to situations when FIR2IR created some declarations in the air
  (mostly fake-overrides)

compiler/testData/codegen/box/multiplatform/hmpp/simple.kt

@@ -7,8 +7,6 @@
 // !LANGUAGE: +MultiPlatformProjects
 // IGNORE_CODEGEN_WITH_IR_FAKE_OVERRIDE_GENERATION: KT-62535
 // TARGET_BACKEND: JVM
-// IGNORE_BACKEND_K2: JVM_IR
-// REASON: K2 incorrectly generates IR for B.bar f/o
 // MODULE: common
 // TARGET_PLATFORM: Common
 

compiler/testData/codegen/box/multiplatform/k2/basic/expectInterfaceInSupertypes2.kt

@@ -2,8 +2,6 @@
 // WITH_STDLIB
 // IGNORE_CODEGEN_WITH_IR_FAKE_OVERRIDE_GENERATION: KT-62535
 // !LANGUAGE: +MultiPlatformProjects
-// IGNORE_BACKEND_K2: ANY
-// REASON: K2 incorrectly generates IR for S2.s3 f/o
 
 // MODULE: common
 // TARGET_PLATFORM: Common