Revert "Rename Extension annotation to ExtensionFunctionType"

This reverts commit 460dad135c.

The old compiler will not see the new runtime correctly. Postponing this until
1.0

idea/idea-completion/testData/basic/multifile/ExcludedClass/ExcludedClass.dependency.kt

@@ -1,5 +1,5 @@
 package somePackage
 
 class ExcludedClass
-// Such strange name here needed to make completion prefix not intersecting with kotlin.ExtensionFunctionType
-class ExctraClass
+// Such strange name here needed to make completion prefix not intersecting with kotlin.Extension
+class ExctraClass

idea/idea-completion/testData/basic/multifile/ExcludedJavaClass/somePackage/ExctraClass.java

@@ -1,6 +1,6 @@
 package somePackage;
 
-// Such strange name here needed to make completion prefix not intersecting with kotlin.ExtensionFunctionType
+// Such strange name here needed to make completion prefix not intersecting with kotlin.Extension
 public class ExctraClass {
 
-}
+}

idea/idea-completion/testData/basic/multifile/NotImportedExtensionFunction2/NotImportedExtensionFunction2.dependency.kt

@@ -6,7 +6,7 @@ fun (() -> Unit)?.helloFun1() {
 fun Function0<Unit>.helloFun2() {
 }
 
-fun @ExtensionFunctionType Function1<String, Unit>.helloFun3() {
+fun @Extension Function1<String, Unit>.helloFun3() {
 }
 
 fun Function1<String, Unit>.helloFun4() {

idea/idea-completion/testData/basic/multifile/NotImportedExtensionFunction3/NotImportedExtensionFunction3.dependency.kt

@@ -6,10 +6,10 @@ fun (String.() -> Unit)?.helloFun1() {
 fun Function0<Unit>.helloFun2() {
 }
 
-fun @ExtensionFunctionType Function1<String, Unit>.helloFun3() {
+fun @Extension Function1<String, Unit>.helloFun3() {
 }
 
-fun @ExtensionFunctionType Function1<Int, Unit>.helloFun4() {
+fun @Extension Function1<Int, Unit>.helloFun4() {
 }
 
 fun Function1<String, Unit>.helloFun5() {