Allow type variable fixation into intersection type if it isn't meaningless (i.e. has one or more final classes, or two or more open classes)

^KT-46186 Fixed

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -29029,6 +29029,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/typeParameters/kt42472.kt");
             }
 
+            @Test
+            @TestMetadata("kt46186.kt")
+            public void testKt46186() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/typeParameters/kt46186.kt");
+            }
+
             @Test
             @TestMetadata("misplacedConstraints.kt")
             public void testMisplacedConstraints() throws Exception {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/types/ConeTypeContext.kt

@@ -261,6 +261,10 @@ interface ConeTypeContext : TypeSystemContext, TypeSystemOptimizationContext, Ty
         return this is ConeClassLikeLookupTag
     }
 
+    override fun TypeConstructorMarker.isInterface(): Boolean {
+        return ((this as? ConeClassLikeLookupTag)?.toClassLikeSymbol()?.fir as? FirClass)?.classKind == ClassKind.INTERFACE
+    }
+
     override fun TypeParameterMarker.getVariance(): TypeVariance {
         require(this is ConeTypeParameterLookupTag)
         return this.symbol.fir.variance.convertVariance()