Move file utils

Fixing IC after moving it from Gradle to the compiler in commit f40a3eff20

compiler/incremental-compilation-impl/src/org/jetbrains/kotlin/incremental/fileUtils.kt

@@ -1,40 +0,0 @@
-/*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.kotlin.incremental
-
-import java.io.File
-
-internal fun File.isJavaFile() =
-        extension.equals("java", ignoreCase = true)
-
-internal fun File.isKotlinFile(): Boolean =
-    extension.let {
-        "kt".equals(it, ignoreCase = true) ||
-        "kts".equals(it, ignoreCase = true)
-    }
-
-internal fun File.isClassFile(): Boolean =
-        extension.equals("class", ignoreCase = true)
-
-internal fun listClassFiles(path: String): Sequence<File> =
-        File(path).walk().filter { it.isFile && it.isClassFile() }
-
-internal fun File.relativeOrCanonical(base: File): String =
-        relativeToOrNull(base)?.path ?: canonicalPath
-
-internal fun Iterable<File>.pathsAsStringRelativeTo(base: File): String =
-        map { it.relativeOrCanonical(base) }.sorted().joinToString()