KT-34414 Make sure completion for suspend functional parameters works too

- Replace `isFunctionType` with `isBuiltinFunctionalType` where it is relevant
- ^KT-34414 Fixed

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/ContextVariablesProvider.kt

@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.idea.completion
 
 import com.intellij.psi.PsiElement
 import com.intellij.util.SmartList
-import org.jetbrains.kotlin.builtins.isFunctionTypeOrSubtype
+import org.jetbrains.kotlin.builtins.isBuiltinFunctionalTypeOrSubtype
 import org.jetbrains.kotlin.descriptors.VariableDescriptor
 import org.jetbrains.kotlin.idea.codeInsight.ReferenceVariantsHelper
 import org.jetbrains.kotlin.idea.util.CallTypeAndReceiver
@@ -39,7 +39,7 @@ class RealContextVariablesProvider(
 ) : ContextVariablesProvider {
 
     val allFunctionTypeVariables by lazy {
-        collectVariables().filter { it.type.isFunctionTypeOrSubtype }
+        collectVariables().filter { it.type.isBuiltinFunctionalTypeOrSubtype }
     }
 
     private fun collectVariables(): Collection<VariableDescriptor> {

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/InsertHandlerProvider.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.idea.completion
 import com.intellij.codeInsight.completion.InsertHandler
 import com.intellij.codeInsight.lookup.LookupElement
 import org.jetbrains.kotlin.builtins.getReturnTypeFromFunctionType
+import org.jetbrains.kotlin.builtins.isBuiltinFunctionalType
 import org.jetbrains.kotlin.builtins.isFunctionType
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.idea.completion.handlers.*
@@ -51,7 +52,7 @@ class InsertHandlerProvider(
                                 if (callType != CallType.SUPER_MEMBERS) { // for super call we don't suggest to generate "super.foo { ... }" (seems to be non-typical use)
                                     val parameter = parameters.single()
                                     val parameterType = parameter.type
-                                    if (parameterType.isFunctionType) {
+                                    if (parameterType.isBuiltinFunctionalType) {
                                         if (getValueParametersCountFromFunctionType(parameterType) <= 1 && !parameter.hasDefaultValue()) {
                                             // otherwise additional item with lambda template is to be added
                                             return KotlinFunctionInsertHandler.Normal(

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/LookupElementFactory.kt

@@ -75,7 +75,7 @@ class LookupElementFactory(
     companion object {
         fun hasSingleFunctionTypeParameter(descriptor: FunctionDescriptor): Boolean {
             val parameter = descriptor.original.valueParameters.singleOrNull() ?: return false
-            return parameter.type.isFunctionType
+            return parameter.type.isBuiltinFunctionalType
         }
 
         val CAST_REQUIRED_COLOR = JBColor(0x4E4040, 0x969696)

idea/idea-completion/testData/basic/common/highOrderFunctions/SuspendFunction.kt

@@ -1,9 +1,12 @@
+interface I : suspend () -> Unit
+
 fun xfoo(p: suspend () -> Unit) {}
 
-fun test() {
+fun test(action: suspend () -> Unit, i: I, notSuspend: () -> Unit) {
     xf<caret>
 }
 
 // EXIST: { itemText:"xfoo", tailText:" {...} (p: suspend () -> Unit) (<root>)", typeText:"Unit" }
-// EXIST: { itemText:"xfoo", tailText:"(p: suspend () -> Unit) (<root>)", typeText:"Unit" }
+// EXIST: { itemText:"xfoo", tailText:"(action) (<root>)", typeText:"Unit" }
+// EXIST: { itemText:"xfoo", tailText:"(i) (<root>)", typeText:"Unit" }
 // NOTHING_ELSE