K1: introduce synthetic assignment checker with deprecation for KT-54305

#KT-54305 Fixed
Related to KT-54309

compiler/testData/diagnostics/tests/syntheticSetFalsePositive.kt

@@ -0,0 +1,15 @@
+// FIR_IDENTICAL
+// FILE: JavaClass.java
+import java.util.List;
+
+public interface JavaClass<E> {
+    List<? extends E> getFoo();
+    void setFoo(List<? extends E> l);
+}
+
+// FILE: main.kt
+
+fun foo(x: JavaClass<in CharSequence>, l: MutableList<out CharSequence>) {
+    x.setFoo(l) // OK
+    x.foo = l // Should be OK, too
+}