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

compiler/testData/asJava/ultraLightClasses/constructors.java

@@ -0,0 +1,54 @@
+public final class TestConstructor /* TestConstructor*/ {
+  private  TestConstructor(int);//  .ctor(int)
+
+}
+
+public final class A /* A*/ {
+  public  A(@org.jetbrains.annotations.NotNull() int[], @org.jetbrains.annotations.NotNull() kotlin.jvm.functions.Function0<kotlin.Unit>);//  .ctor(int[], kotlin.jvm.functions.Function0<kotlin.Unit>)
+
+}
+
+public final class B /* B*/ {
+}
+
+public final class Outer /* Outer*/ {
+  public  Outer();//  .ctor()
+
+
+
+  class Inner ...
+  
+    class Nested ...
+  
+  }
+
+public final class Inner /* Outer.Inner*/ {
+  public  Inner(int, @org.jetbrains.annotations.NotNull() java.lang.String);//  .ctor(int, java.lang.String)
+
+}
+
+public static final class Nested /* Outer.Nested*/ {
+  public  Nested();//  .ctor()
+
+  public  Nested(int, @org.jetbrains.annotations.NotNull() java.lang.String);//  .ctor(int, java.lang.String)
+
+}
+
+public abstract class A /* A*/ {
+  @org.jetbrains.annotations.Nullable()
+  private final java.lang.String x;
+
+  @org.jetbrains.annotations.Nullable()
+  public final java.lang.String getX();//  getX()
+
+  private  A(@org.jetbrains.annotations.Nullable() java.lang.String);//  .ctor(java.lang.String)
+
+
+  class C ...
+  
+  }
+
+public static final class C /* A.C*/ extends A {
+  public  C();//  .ctor()
+
+}