Allow impl declarations to have flexible types

Types of the corresponding parameters (or type parameter bounds, types
in supertypes, etc) are now compatible not only if they're equal, but
also if values of those types are mutually assignable (if "a" is subtype
of "b" and "b" is subtype of "a")

 #KT-17005 Fixed

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -13102,6 +13102,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("implDynamic.kt")
+            public void testImplDynamic() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/implDynamic.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("implFakeOverride.kt")
             public void testImplFakeOverride() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/implFakeOverride.kt");
@@ -13245,6 +13251,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/tests/multiplatform/java"), Pattern.compile("^(.+)\\.kt$"), TargetBackend.ANY, true);
                 }
 
+                @TestMetadata("flexibleTypes.kt")
+                public void testFlexibleTypes() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/java/flexibleTypes.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("parameterNames.kt")
                 public void testParameterNames() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/multiplatform/java/parameterNames.kt");