Minor. Rename FunctionClassDescriptor#functionKind -> functionTypeKind

This commit is needed for the following commit.
There we will restore the compatibility API with Android IDEA plugin

compiler/backend/src/org/jetbrains/kotlin/codegen/state/KotlinTypeMapper.kt

@@ -342,8 +342,8 @@ class KotlinTypeMapper @JvmOverloads constructor(
 
         if (classDescriptor is FunctionClassDescriptor) {
             if (classDescriptor.hasBigArity ||
-                classDescriptor.functionKind == FunctionTypeKind.KFunction ||
-                classDescriptor.functionKind == FunctionTypeKind.KSuspendFunction
+                classDescriptor.functionTypeKind == FunctionTypeKind.KFunction ||
+                classDescriptor.functionTypeKind == FunctionTypeKind.KSuspendFunction
             ) {
                 // kotlin.reflect.KFunction{n}<P1, ..., Pn, R> is mapped to kotlin.reflect.KFunction<R> (for all n), and
                 // kotlin.Function{n}<P1, ..., Pn, R> is mapped to kotlin.jvm.functions.FunctionN<R> (for n > 22).

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/SuspendFunctionAsSupertypeChecker.kt

@@ -22,14 +22,14 @@ object SuspendFunctionAsSupertypeChecker : DeclarationChecker {
         val functionalSupertypes = descriptor.getAllSuperClassifiers().filterIsInstance<FunctionClassDescriptor>().toList()
 
         if (functionalSupertypes.none {
-                it.functionKind == FunctionTypeKind.SuspendFunction ||
-                        it.functionKind == FunctionTypeKind.KSuspendFunction
+                it.functionTypeKind == FunctionTypeKind.SuspendFunction ||
+                        it.functionTypeKind == FunctionTypeKind.KSuspendFunction
             }
         ) return
 
         if (functionalSupertypes.any {
-                it.functionKind == FunctionTypeKind.Function ||
-                        it.functionKind == FunctionTypeKind.KFunction
+                it.functionTypeKind == FunctionTypeKind.Function ||
+                        it.functionTypeKind == FunctionTypeKind.KFunction
             }
         ) {
             val reportOn = (declaration as? KtClassOrObject)?.getSuperTypeList() ?: declaration