[klib] Test signature descriptions in irText tests

KT-59486

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IdSignature.kt

@@ -519,6 +519,8 @@ sealed class IdSignature {
         override val isPubliclyVisible: Boolean
             get() = memberSignature.isPubliclyVisible
 
+        override fun asPublic(): CommonSignature? = memberSignature.asPublic()
+
         override fun topLevelSignature(): IdSignature =
             memberSignature.topLevelSignature()