FIR: introduce MANY_*_MEMBER_NOT_IMPLEMENTED diagnostic

compiler/testData/diagnostics/tests/override/FakeOverrideDifferentDeclarationSignatures.fir.kt

@@ -1,11 +0,0 @@
-interface A {
-    fun f(): String = "string"
-}
-
-open class B {
-    open fun f(): CharSequence = "charSequence"
-}
-
-class C : B(), A
-
-val obj: A = object : B(), A {}

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface A {
     fun f(): String = "string"
 }

compiler/testData/diagnostics/tests/override/ObjectDelegationManyImpl.fir.kt

@@ -10,4 +10,4 @@ object Impl : D, E {
     override fun foo() {}
 }
 
-val obj: D = object : D by Impl, E by Impl {}
+val obj: D = <!MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>object<!> : D by Impl, E by Impl {}

compiler/testData/diagnostics/tests/override/ParentInheritsManyImplementations.fir.kt

@@ -1,17 +0,0 @@
-package d
-
-interface A {
-    fun foo() = 1
-}
-
-interface B {
-    fun foo() = 2
-}
-
-open class C : A, B {}
-
-interface E {
-    fun foo(): Int
-}
-
-class D : C() {}

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 package d
 
 interface A {