Stub generation infrastructure (except for metadata generation) for KAPT+K2

This commit includes the basic Java stubs generation infrastructure and
the corresponding tests. The main entry point is called
Kapt4StubGenerator. Calls to it from production code will be added in a
separate commit.

 #KT-51982

plugins/kapt3/kapt3-compiler/testData/converter/genericParameters.fir.txt

@@ -0,0 +1,28 @@
+@kotlin.Metadata()
+public final class MappedList<T extends java.lang.Object, R extends java.lang.Object> extends kotlin.collections.AbstractList<R> implements java.util.List<R>, kotlin.jvm.internal.markers.KMappedMarker {
+    @org.jetbrains.annotations.NotNull()
+    private final java.util.List<T> list = null;
+    @org.jetbrains.annotations.NotNull()
+    private final kotlin.jvm.functions.Function1<T, R> function = null;
+
+    public MappedList(@org.jetbrains.annotations.NotNull()
+    java.util.List<? extends T> list, @org.jetbrains.annotations.NotNull()
+    kotlin.jvm.functions.Function1<? super T, ? extends R> function) {
+        super();
+    }
+
+    @org.jetbrains.annotations.NotNull()
+    public final java.util.List<T> getList() {
+        return null;
+    }
+
+    @java.lang.Override()
+    public R get(int index) {
+        return null;
+    }
+
+    @java.lang.Override()
+    public int getSize() {
+        return 0;
+    }
+}