Change runtime component from "Core" to "Main"

This is needed to allow the old compiler have the new runtime libraries in the
classpath. See the previous commit for a more elaborate explanation

libraries/tools/kotlin-maven-plugin-test/src/it/test-kotlin-version-in-manifest/src/main/kotlin/test.kt

@@ -17,7 +17,7 @@ val LIBRARIES = listOf(
 
 const val KOTLIN_VERSION = "Kotlin-Version"
 const val KOTLIN_RUNTIME_COMPONENT = "Kotlin-Runtime-Component"
-const val KOTLIN_RUNTIME_COMPONENT_VALUE = "Core"
+const val KOTLIN_RUNTIME_COMPONENT_VALUE = "Main"
 val KOTLIN_VERSION_VALUE = with(KotlinVersion.CURRENT) { "$major.$minor" }
 
 fun main(args: Array<String>) {

libraries/tools/runtime/pom.xml

@@ -114,7 +114,7 @@
                     <archive>
                         <manifestEntries>
                             <Kotlin-Version>${kotlin.language.version}</Kotlin-Version>
-                            <Kotlin-Runtime-Component>Core</Kotlin-Runtime-Component>
+                            <Kotlin-Runtime-Component>Main</Kotlin-Runtime-Component>
                         </manifestEntries>
                     </archive>
                 </configuration>