Tests: do not report backend diagnostics if there's frontend error

In most affected tests, the backend diagnostic such as "conflicting JVM
signature" or "accidental override" is directly caused by some already
existing error reported by frontend, so it doesn't make sense to check
backend diagnostics there.

Tests where that was not the case were moved/copied to
`testsWithJvmBackend`.

compiler/testData/diagnostics/tests/override/Generics.kt

@@ -49,12 +49,12 @@ abstract class MyAbstractClass1 : MyTrait<Int>, MyAbstractClass<String>() {
 abstract class MyLegalAbstractClass1 : MyTrait<Int>, MyAbstractClass<String>() {}
 
 <!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class MyIllegalClass2<!><T>(t : T) : MyTrait<Int>, MyAbstractClass<Int>() {
-    <!ACCIDENTAL_OVERRIDE!>fun foo(t: T)<!> = t
-    <!ACCIDENTAL_OVERRIDE!>fun bar(t: T)<!> = t
+    fun foo(t: T) = t
+    fun bar(t: T) = t
     <!CONFLICTING_OVERLOADS!>val <<!TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER!>R<!>> pr : T<!> = t
 }
 abstract class MyLegalAbstractClass2<T>(t : T) : MyTrait<Int>, MyAbstractClass<Int>() {
-    <!ACCIDENTAL_OVERRIDE!>fun foo(t: T)<!> = t
-    <!ACCIDENTAL_OVERRIDE!>fun bar(t: T)<!> = t
+    fun foo(t: T) = t
+    fun bar(t: T) = t
     <!CONFLICTING_OVERLOADS!>val <<!TYPE_PARAMETER_OF_PROPERTY_NOT_USED_IN_RECEIVER!>R<!>> pr : T<!> = t
-}
+}

compiler/testData/diagnostics/tests/override/InheritingJavaClassWithRawTypeInOverrideSignature.kt

@@ -17,4 +17,4 @@ public abstract class B implements A<String> {
 public class C extends B implements A<String> {}
 
 // FILE: Main.kt
-<!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class <!CONFLICTING_INHERITED_JVM_DECLARATIONS!>X<!><!> : C() // false positive in K1, OK in K2
+<!ABSTRACT_CLASS_MEMBER_NOT_IMPLEMENTED!>class X<!> : C() // false positive in K1, OK in K2