Remove old plaintext StubGenerator and introduce Stub IR-based generator

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/CodeBuilders.kt

@@ -100,13 +100,4 @@ inline fun buildKotlinCodeLines(scope: KotlinScope, block: KotlinCodeBuilder.()
     val builder = KotlinCodeBuilder(scope)
     builder.block()
     return builder.build()
-}
-
-interface StubGenerationContext {
-    val nativeBridges: NativeBridges
-    fun addTopLevelDeclaration(lines: List<String>)
-}
-
-interface KotlinStub {
-    fun generate(context: StubGenerationContext): Sequence<String>
 }

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/CodeUtils.kt

@@ -71,22 +71,5 @@ private val charactersAllowedInKotlinStringLiterals: Set<Char> = mutableSetOf<Ch
     addAll(listOf('_', '@', ':', ';', '.', ',', '{', '}', '=', '[', ']', '^', '#', '*', ' ', '(', ')'))
 }
 
-fun block(header: String, lines: Iterable<String>) = block(header, lines.asSequence())
-
-fun block(header: String, lines: Sequence<String>) =
-        sequenceOf("$header {") +
-                lines.map { "    $it" } +
-                sequenceOf("}")
-
 val annotationForUnableToImport
     get() = "@Deprecated(${"Unable to import this declaration".quoteAsKotlinLiteral()}, level = DeprecationLevel.ERROR)"
-
-fun String.applyToStrings(vararg arguments: String) =
-        "${this}(${arguments.joinToString { it.quoteAsKotlinLiteral() }})"
-
-fun List<KotlinParameter>.renderParameters(scope: KotlinScope) = buildString {
-    this@renderParameters.renderParametersTo(scope, this)
-}
-
-fun List<KotlinParameter>.renderParametersTo(scope: KotlinScope, buffer: Appendable) =
-        this.joinTo(buffer, ", ") { it.render(scope) }

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/KotlinCodeModel.kt

@@ -284,7 +284,7 @@ abstract class KotlinFile(
 
     override fun declare(classifier: Classifier): String {
         if (classifier.pkg != this.pkg) {
-            throw IllegalArgumentException("wrong package; expected '$pkg', got '${classifier.pkg}'")
+            throw IllegalArgumentException("wrong package for classifier ${classifier.fqName}; expected '$pkg', got '${classifier.pkg}'")
         }
 
         if (!classifier.isTopLevel) {