Refactor Main-Class computation in CLI for JVM with .jar outputs

Compute FQ name of the main class right after running the analysis and
before invoking codegen. This is needed because MainFunctionDetector
depends on BindingContext, and JVM IR needs to clear BindingContext as
soon as it's not necessary to reduce peak memory usage, thus breaking
any usages of data from it after the codegen.

Also refactor and use the extracted, but not properly reused previously,
copy of findMainClass in findMainClass.kt.

Note that this replaces NPE in KT-42868 with an UOE.

idea/jvm-debugger/jvm-debugger-test/test/org/jetbrains/kotlin/idea/debugger/test/DebuggerTestCompilerFacility.kt

@@ -10,7 +10,6 @@ import com.intellij.openapi.module.Module
 import com.intellij.openapi.roots.LibraryOrderEntry
 import com.intellij.openapi.roots.ModuleRootManager
 import com.intellij.openapi.roots.OrderRootType
-import com.intellij.openapi.roots.libraries.ui.OrderRoot
 import com.intellij.openapi.util.io.FileUtil
 import com.intellij.openapi.vfs.LocalFileSystem
 import com.intellij.openapi.vfs.VirtualFile
@@ -32,6 +31,7 @@ import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.config.JVMConfigurationKeys
 import org.jetbrains.kotlin.config.JvmTarget
 import org.jetbrains.kotlin.diagnostics.rendering.DefaultErrorMessages
+import org.jetbrains.kotlin.idea.resolve.getLanguageVersionSettings
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.test.KotlinBaseTest.TestFile
 import org.jetbrains.kotlin.test.MockLibraryUtil
@@ -198,7 +198,8 @@ class DebuggerTestCompilerFacility(
 
         state.factory.writeAllTo(classesDir)
 
-        return findMainClass(state, files)?.asString() ?: error("Cannot find main class name")
+        return findMainClass(bindingContext, resolutionFacade.getLanguageVersionSettings(), files)?.asString()
+            ?: error("Cannot find main class name")
     }
 
     private fun getClasspath(module: Module): List<String> {