[CLI] K2JVMCompilerArguments: Model classpath as Array<String>

to allow interning individual file-path arguments on the IDE

KTIJ-24976

plugins/fir-plugin-prototype/fir-plugin-ic-test/tests/org/jetbrains/kotlin/incremental/AbstractIncrementalFirJvmCompilerRunnerTest.kt

@@ -35,7 +35,7 @@ abstract class AbstractIncrementalFirJvmWithPluginCompilerRunnerTest : AbstractI
             val annotationsJar = findJar(ANNOTATIONS_JAR_DIR, ANNOTATIONS_JAR_NAME, ":plugins:fir-plugin-prototype:plugin-annotations:jar")
             val pluginJar = findJar(PLUGIN_JAR_DIR, PLUGIN_JAR_NAME, ":plugins:fir-plugin-prototype:jar")
 
-            classpath += "${File.pathSeparator}$annotationsJar"
+            classpath = classpath?.plus(annotationsJar)
             pluginClasspaths = arrayOf(pluginJar)
         }
 

plugins/jvm-abi-gen/test/org/jetbrains/kotlin/jvm/abi/BaseJvmAbiTest.kt

@@ -74,7 +74,7 @@ abstract class BaseJvmAbiTest : TestCase() {
         val compiler = K2JVMCompiler()
         val args = compiler.createArguments().apply {
             freeArgs = listOf(compilation.srcDir.canonicalPath)
-            classpath = (abiDependencies + kotlinJvmStdlib).joinToString(File.pathSeparator) { it.canonicalPath }
+            classpath = (abiDependencies + kotlinJvmStdlib).map { it.canonicalPath }.toTypedArray()
             pluginClasspaths = arrayOf(abiPluginJar.canonicalPath)
             pluginOptions = listOfNotNull(
                 abiOption(JvmAbiCommandLineProcessor.OUTPUT_PATH_OPTION.optionName, compilation.abiDir.canonicalPath),