[KMP] Implement ACTUAL_TYPE_ALIAS_TO_NOTHING/TO_NULLABLE_TYPE errors

^KT-60650 Done

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -3399,6 +3399,18 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.ACTUAL_TYPE_ALIAS_TO_NULLABLE_TYPE) { firDiagnostic ->
+        ActualTypeAliasToNullableTypeImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
+    add(FirErrors.ACTUAL_TYPE_ALIAS_TO_NOTHING) { firDiagnostic ->
+        ActualTypeAliasToNothingImpl(
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS) { firDiagnostic ->
         ActualFunctionWithDefaultArgumentsImpl(
             firDiagnostic as KtPsiDiagnostic,

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -2391,6 +2391,14 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = ActualTypeAliasWithComplexSubstitution::class
     }
 
+    interface ActualTypeAliasToNullableType : KtFirDiagnostic<KtTypeAlias> {
+        override val diagnosticClass get() = ActualTypeAliasToNullableType::class
+    }
+
+    interface ActualTypeAliasToNothing : KtFirDiagnostic<KtTypeAlias> {
+        override val diagnosticClass get() = ActualTypeAliasToNothing::class
+    }
+
     interface ActualFunctionWithDefaultArguments : KtFirDiagnostic<PsiElement> {
         override val diagnosticClass get() = ActualFunctionWithDefaultArguments::class
     }

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -2884,6 +2884,16 @@ internal class ActualTypeAliasWithComplexSubstitutionImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<KtTypeAlias>(firDiagnostic, token), KtFirDiagnostic.ActualTypeAliasWithComplexSubstitution
 
+internal class ActualTypeAliasToNullableTypeImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtTypeAlias>(firDiagnostic, token), KtFirDiagnostic.ActualTypeAliasToNullableType
+
+internal class ActualTypeAliasToNothingImpl(
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<KtTypeAlias>(firDiagnostic, token), KtFirDiagnostic.ActualTypeAliasToNothing
+
 internal class ActualFunctionWithDefaultArgumentsImpl(
     firDiagnostic: KtPsiDiagnostic,
     token: KtLifetimeToken,