[Gradle, JS] Remove webpack 4 support

^KT-57387 fixed

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/PropertiesProvider.kt

@@ -41,7 +41,6 @@ import org.jetbrains.kotlin.gradle.plugin.PropertiesProvider.PropertyNames.KOTLI
 import org.jetbrains.kotlin.gradle.plugin.statistics.KotlinBuildStatsService
 import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinIrJsGeneratedTSValidationStrategy
 import org.jetbrains.kotlin.gradle.targets.js.ir.KotlinJsIrOutputGranularity
-import org.jetbrains.kotlin.gradle.targets.js.webpack.WebpackMajorVersion
 import org.jetbrains.kotlin.gradle.targets.native.DisabledNativeTargetsReporter
 import org.jetbrains.kotlin.gradle.tasks.*
 import org.jetbrains.kotlin.gradle.utils.NativeCompilerDownloader

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/js/webpack/WebpackMajorVersion.kt

@@ -1,45 +0,0 @@
-/*
- * Copyright 2010-2021 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.gradle.targets.js.webpack
-
-enum class WebpackMajorVersion(
-    val value: String
-) {
-    V4("4"),
-    V5("5");
-
-    companion object {
-        val DEFAULT = V5
-
-        const val webpackMajorVersion = "kotlin.js.webpack.major.version"
-
-        const val warningMessage = "Default webpack version now is 5. Support of webpack 4 is deprecated."
-
-        var webpackVersionWarning = false
-
-        fun byArgumentOrNull(argument: String): WebpackMajorVersion? =
-            when (argument) {
-                "4" -> V4
-                "5" -> V5
-                else -> null
-            }
-
-        fun byArgument(argument: String): WebpackMajorVersion =
-            byArgumentOrNull(argument)
-                ?: throw IllegalArgumentException(
-                    "This webpack major version is not supported. Use [${WebpackMajorVersion.values().toList().joinToString { it.value }}]"
-                )
-
-        fun <T> WebpackMajorVersion.choose(
-            defaultValue: T,
-            v4Value: T
-        ): T =
-            when (this) {
-                V5 -> defaultValue
-                V4 -> v4Value
-            }
-    }
-}