Add FIR enhancement tests, fix some exceptions / problems around them

Test data and tests themselves are based on
compiler/testData/loadJava/compiledJava

compiler/testData/loadJava/compiledJava/signaturePropagation/ArraysInSubtypes.fir.txt

@@ -0,0 +1,2 @@
+public abstract interface ArraysInSubtypes : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/MethodTypeParameterErased.fir.txt

@@ -0,0 +1,2 @@
+public abstract interface MethodTypeParameterErased : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/RawSuperType.fir.txt

@@ -0,0 +1,2 @@
+public open class RawSuperType : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/RawSuperTypeWithBound.fir.txt

@@ -0,0 +1,2 @@
+public open class RawSuperTypeWithBound : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/RawSuperTypeWithRecursiveBound.fir.txt

@@ -0,0 +1,2 @@
+public open class RawSuperTypeWithRecursiveBound : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/RawSuperTypeWithRecursiveBoundMultipleParameters.fir.txt

@@ -0,0 +1,2 @@
+public open class RawSuperTypeWithRecursiveBoundMultipleParameters : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/ReturnInnerSubclassOfSupersInner.fir.txt

@@ -0,0 +1,2 @@
+public abstract interface ReturnInnerSubclassOfSupersInner : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/SubclassWithRawType.fir.txt

@@ -0,0 +1,2 @@
+public abstract interface SubclassWithRawType : R|java/lang/Object| {
+}

compiler/testData/loadJava/compiledJava/signaturePropagation/TwoSuperclassesInconsistentGenericTypes.fir.txt

@@ -0,0 +1,6 @@
+public abstract interface TwoSuperclassesInconsistentGenericTypes : R|java/lang/Object| {
+    public abstract operator function foo(): R|ft<java/util/List<ft<java/lang/String, java/lang/String?>>, java/util/List<ft<java/lang/String, java/lang/String?>>>|
+
+    public abstract operator function dummy(): R|kotlin/Unit|
+
+}