FIR2IR: Rework resulted overridden-relation structure

The difference is how we deal with intermediate fake overrides
E.g., in case

interface A { /* $1 */ fun foo() }
interface B : A {
     /* $2 */ fake_override fun foo()
}
interface C : B {
   /* $3 */ override fun foo()
}

We've got FIR declarations only for $1 and $3, but we've got
a fake override for $2 in IR.

Previously, override $3 had $1 as its overridden IR symbol, just because
FIR declaration of $3 doesn't know anything about $2.

Now, when generating IR for $2, we save the necessary information
and using it for $3, so it has $2 as overridden.

So, it's consistent with the overridden structure of FE 1.0 and this
structure is necessary prerequisite for proper building of bridges
for special built-ins.

compiler/testData/codegen/bytecodeText/builtinFunctions/genericParameterBridge/abstractList.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 abstract class A3<W> : java.util.AbstractList<W>()
 abstract class A4<W> : java.util.AbstractList<W>() {
     override fun contains(o: W): Boolean {

compiler/testData/codegen/bytecodeText/interfaces/traitImplGeneratedOnce.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 interface A {
     fun foo() = 42
 }

compiler/testData/codegen/bytecodeText/mapGetOrDefault.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // JVM_TARGET: 1.8
 // WITH_RUNTIME
 // FULL_JDK
@@ -38,4 +37,4 @@ class MyMap: TestMap<String, String>()
 
 // JVM_IR_TEMPLATES:
 // 1 public bridge getOrDefault\(Ljava/lang/String;Ljava/lang/String;\)Ljava/lang/String;
-// 1 public final bridge getOrDefault\(Ljava/lang/Object;Ljava/lang/String;\)Ljava/lang/String;
+// 1 public final bridge getOrDefault\(Ljava/lang/Object;Ljava/lang/String;\)Ljava/lang/String;