[FIR IDE] Add Fir lightclasses tests and fix FindUsages tests

compiler/testData/asJava/lightClasses/nullabilityAnnotations/ClassWithConstructor.kt

@@ -3,4 +3,6 @@
 class ClassWithConstructor(
         nullable: String?,
         notNull: String
-)
+)
+
+// FIR_COMPARISON

compiler/testData/asJava/lightClasses/nullabilityAnnotations/OverrideAnyWithUnit.kt

@@ -8,4 +8,5 @@ class C : Base {
     override fun foo(): Unit {}
 }
 
-// LAZINESS:NoLaziness
+// LAZINESS:NoLaziness
+// FIR_COMPARISON

compiler/testData/asJava/lightClasses/nullabilityAnnotations/Synthetic.kt

@@ -8,4 +8,6 @@ class Synthetic {
     }
 
     private fun foo() {}
-}
+}
+
+// FIR_COMPARISON

compiler/testData/asJava/lightClasses/nullabilityAnnotations/UnitAsGenericArgument.kt

@@ -7,4 +7,5 @@ interface Base<T> {
 class C : Base<Unit> {
     override fun foo(t: Unit) {}
 }
-// LAZINESS:NoLaziness
+// LAZINESS:NoLaziness
+// FIR_COMPARISON

compiler/testData/asJava/lightClasses/nullabilityAnnotations/UnitParameter.kt

@@ -1,3 +1,5 @@
 // UnitParameterKt
 
-fun foo(s: Unit) {}
+fun foo(s: Unit) {}
+
+// FIR_COMPARISON

compiler/testData/asJava/lightClasses/nullabilityAnnotations/VoidReturn.kt

@@ -1,3 +1,5 @@
 // VoidReturnKt
 
-fun foo(g: String) {}
+fun foo(g: String) {}
+
+// FIR_COMPARISON