Introduce inline-only functions

They have private visibility in bytecode

compiler/testData/codegen/bytecodeListing/inlineOnly.kt

@@ -0,0 +1,17 @@
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.jvm.internal.InlineOnly
+inline fun foo() { }
+
+inline fun <T> bar() { }
+
+inline fun <U, reified V> baz() {}
+
+class Foo {
+    @Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+    @kotlin.jvm.internal.InlineOnly
+    inline fun foo() { }
+
+    inline fun <T> bar() { }
+
+    inline fun <U, reified V> baz() {}
+}

compiler/testData/codegen/bytecodeListing/inlineOnly.txt

@@ -0,0 +1,14 @@
+@kotlin.jvm.internal.KotlinClass
+public final class Foo {
+    public method <init>(): void
+    public final method bar(): void
+    private final method baz(): void
+    private final @kotlin.jvm.internal.InlineOnly method foo(): void
+}
+
+@kotlin.jvm.internal.KotlinFileFacade
+public final class InlineOnlyKt {
+    public final static method bar(): void
+    private final static method baz(): void
+    private final static @kotlin.jvm.internal.InlineOnly method foo(): void
+}