FIR Java: fix constructor enhancements

Before this commit,
we generated regular member functions as constructor enhancement.
Now, we generate constructors as constructor enhancement.

compiler/testData/loadJava/compiledJava/kotlinSignature/ConstructorWithNewTypeParams.fir.txt

@@ -1,4 +1,4 @@
 public open class ConstructorWithNewTypeParams<T> : R|java/lang/Object| {
-    public final fun ConstructorWithNewTypeParams(first: R|ft<U, U?>|!): R|test/ConstructorWithNewTypeParams|
+    public constructor(first: R|ft<U, U?>|!): R|test/ConstructorWithNewTypeParams|
 
 }

compiler/testData/loadJava/compiledJava/kotlinSignature/ConstructorWithParentTypeParams.fir.txt

@@ -1,4 +1,4 @@
 public open class ConstructorWithParentTypeParams<T> : R|java/lang/Object| {
-    public final fun ConstructorWithParentTypeParams(first: R|ft<T, T?>|!): R|test/ConstructorWithParentTypeParams|
+    public constructor(first: R|ft<T, T?>|!): R|test/ConstructorWithParentTypeParams|
 
 }

compiler/testData/loadJava/compiledJava/kotlinSignature/ConstructorWithSeveralParams.fir.txt

@@ -1,4 +1,4 @@
 public open class ConstructorWithSeveralParams : R|java/lang/Object| {
-    public final fun ConstructorWithSeveralParams(integer: R|ft<kotlin/Int, kotlin/Int?>|!, intBasic: R|kotlin/Int|, collection: R|ft<java/util/ArrayList<ft<kotlin/String, kotlin/String?>>, java/util/ArrayList<ft<kotlin/String, kotlin/String?>>?>|!): R|test/ConstructorWithSeveralParams|
+    public constructor(integer: R|ft<kotlin/Int, kotlin/Int?>|!, intBasic: R|kotlin/Int|, collection: R|ft<java/util/ArrayList<ft<kotlin/String, kotlin/String?>>, java/util/ArrayList<ft<kotlin/String, kotlin/String?>>?>|!): R|test/ConstructorWithSeveralParams|
 
 }

compiler/testData/loadJava/compiledJava/kotlinSignature/ConstructorWithoutParams.fir.txt

@@ -1,4 +1,4 @@
 public open class ConstructorWithoutParams : R|java/lang/Object| {
-    public final fun ConstructorWithoutParams(): R|test/ConstructorWithoutParams|
+    public constructor(): R|test/ConstructorWithoutParams|
 
 }