Apply scripting subplugin in gradle mpp plugin, so scripts could be added to mpp sources

#KT-30679 fixed

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/NewMultiplatformIT.kt

@@ -398,6 +398,7 @@ class NewMultiplatformIT : BaseGradleIT() {
                     arrayOf(
                         it + "com/example/lib/CommonKt.class",
                         it + "com/example/lib/MainKt.class",
+                        it + "Script.class",
                         it + "META-INF/new-mpp-lib-with-tests.kotlin_module"
                     )
                 },

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/new-mpp-lib-with-tests/build.gradle

@@ -37,7 +37,8 @@ kotlin {
         }
         configure([main, jvmWithoutJavaMain]) {
         	dependencies {
-        		implementation 'org.jetbrains.kotlin:kotlin-stdlib'
+				implementation 'org.jetbrains.kotlin:kotlin-stdlib'
+        		implementation 'org.jetbrains.kotlin:kotlin-script-runtime'
         	}
         }
         configure([test, jvmWithoutJavaTest]) {

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/new-mpp-lib-with-tests/build.gradle.kts.alternative

@@ -29,6 +29,7 @@ kotlin {
         configure(listOf(main, jvmWithoutJavaMain)) {
         	dependencies {
         		implementation(kotlin("stdlib"))
+        		implementation(kotlin("script-runtime"))
         	}
         }
 

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/new-mpp-lib-with-tests/src/jvmWithoutJavaMain/kotlin/script.kts

@@ -0,0 +1,2 @@
+
+val x = 0

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinMultiplatformPlugin.kt

@@ -27,6 +27,7 @@ import org.jetbrains.kotlin.gradle.dsl.kotlinExtension
 import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
 import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.plugin.sources.DefaultLanguageSettingsBuilder
+import org.jetbrains.kotlin.gradle.scripting.internal.ScriptingGradleSubplugin
 import org.jetbrains.kotlin.gradle.utils.SingleWarningPerBuild
 import org.jetbrains.kotlin.gradle.utils.checkGradleCompatibility
 import org.jetbrains.kotlin.gradle.utils.lowerCamelCaseName
@@ -89,6 +90,8 @@ class KotlinMultiplatformPlugin(
         // propagate compiler plugin options to the source set language settings
         setupCompilerPluginOptions(project)
 
+        project.pluginManager.apply(ScriptingGradleSubplugin::class.java)
+
         UnusedSourceSetsChecker.checkSourceSets(project)
     }
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/scripting/internal/ScriptingGradleSubplugin.kt

@@ -16,6 +16,7 @@ import org.gradle.api.plugins.JavaPluginConvention
 import org.gradle.api.tasks.compile.AbstractCompile
 import org.jetbrains.kotlin.cli.common.messages.MessageRenderer
 import org.jetbrains.kotlin.cli.common.messages.PrintingMessageCollector
+import org.jetbrains.kotlin.gradle.dsl.KotlinJvmCompile
 import org.jetbrains.kotlin.gradle.internal.KaptGenerateStubsTask
 import org.jetbrains.kotlin.gradle.plugin.*
 import org.jetbrains.kotlin.gradle.scripting.ScriptingExtension
@@ -51,11 +52,15 @@ class ScriptingGradleSubplugin : Plugin<Project> {
 
                     if (task !is KaptGenerateStubsTask) {
 
-                        val discoveryClasspathConfigurationName = getDiscoveryClasspathConfigurationName(task.sourceSetName)
+                        try {
-                        project.configurations.findByName(discoveryClasspathConfigurationName)?.let { _ ->
+                            val discoveryClasspathConfigurationName = getDiscoveryClasspathConfigurationName(task.sourceSetName)
-                            configureScriptsExtensions(project, javaPluginConvention, task.sourceSetName)
+                            project.configurations.findByName(discoveryClasspathConfigurationName)?.let { _ ->
+                                configureScriptsExtensions(project, javaPluginConvention, task.sourceSetName)
+                            }
+                                ?: project.logger.warn("kotlin scripting plugin: $project.${task.name} - configuration not found: $discoveryClasspathConfigurationName, $MISCONFIGURATION_MESSAGE_SUFFIX")
+                        } catch (e: IllegalStateException) {
+                            project.logger.warn("kotlin scripting plugin: applied in the non-supported environment (error received: ${e.message})")
                         }
-                            ?: project.logger.warn("kotlin scripting plugin: $project.${task.name} - configuration not found: $discoveryClasspathConfigurationName, $MISCONFIGURATION_MESSAGE_SUFFIX")
                     }
                 }
                 if (useLazyTaskConfiguration) {
@@ -204,7 +209,7 @@ class ScriptingKotlinGradleSubplugin : KotlinGradleSubplugin<AbstractCompile> {
     }
 
     override fun isApplicable(project: Project, task: AbstractCompile) =
-        ScriptingGradleSubplugin.isEnabled(project)
+        task is KotlinJvmCompile && ScriptingGradleSubplugin.isEnabled(project)
 
     override fun apply(
         project: Project,