[FIR] Extract FirExtensionPointService to separate file

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionPoint.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.extensions
+
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.name.Name
+
+abstract class FirExtensionPoint(val session: FirSession) {
+    abstract val name: FirExtensionPointName
+
+    fun interface Factory<P : FirExtensionPoint> {
+        fun create(session: FirSession): P
+    }
+}
+
+data class FirExtensionPointName(val name: Name) {
+    constructor(name: String) : this(Name.identifier(name))
+}

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/extensions/FirExtensionPointService.kt

@@ -9,23 +9,10 @@ import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.FirSessionComponent
 import org.jetbrains.kotlin.fir.utils.ComponentArrayOwner
 import org.jetbrains.kotlin.fir.utils.ComponentTypeRegistry
-import org.jetbrains.kotlin.name.Name
 import kotlin.properties.ReadOnlyProperty
 import kotlin.reflect.KClass
 import kotlin.reflect.KProperty
 
-abstract class FirExtensionPoint(val session: FirSession) {
-    abstract val name: FirExtensionPointName
-
-    fun interface Factory<P : FirExtensionPoint> {
-        fun create(session: FirSession): P
-    }
-}
-
-data class FirExtensionPointName(val name: Name) {
-    constructor(name: String) : this(Name.identifier(name))
-}
-
 @Suppress("EXPERIMENTAL_FEATURE_WARNING")
 inline class FirRegisteredExtension<P : FirExtensionPoint>(val extensions: List<P>)
 
@@ -51,4 +38,4 @@ class FirExtensionPointService(
     }
 }
 
-val FirSession.extensionPointService: FirExtensionPointService by FirSession.sessionComponentAccessor()
+val FirSession.extensionPointService: FirExtensionPointService by FirSession.sessionComponentAccessor()