Ignore synthetic annotation classes produced by directly instantiated annotations

[ZacSweers]

In Kotlin 1.6.0, synthetic annotation classes are present in the API dump and I think they should be automatically excluded.

I can manually ignore them, but it's tedious and prone to breaking due to the mangled names.

Example from here: slackhq/EitherNet#29

public synthetic class com/slack/eithernet/AnnotationsKt$annotationImpl$com_slack_eithernet_StatusCode$0 : com/slack/eithernet/StatusCode {
	public fun <init> (I)V
	public final synthetic fun annotationType ()Ljava/lang/Class;
	public final fun equals (Ljava/lang/Object;)Z
	public final fun hashCode ()I
	public final fun toString ()Ljava/lang/String;
	public final synthetic fun value ()I
}