[IR] Add the description field to CommonIdSignature

This field shall be used for storing a human-readable representation
of the declaration, that would be a mangled name for now.

This field is not yet serialized. Serialization will be implemented in
follow-up commits.

See KT-59486

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/ic/IdSignatureSerialization.kt

@@ -88,7 +88,13 @@ internal class IdSignatureSerialization(private val library: KotlinLibraryHeader
                         null
                     }
                     val mask = input.readInt64()
-                    return IdSignature.CommonSignature(packageFqName, declarationFqName, id, mask)
+                    return IdSignature.CommonSignature(
+                        packageFqName = packageFqName,
+                        declarationFqName = declarationFqName,
+                        id = id,
+                        mask = mask,
+                        description = null, // TODO(KT-59486): Deserialize mangled name and save it here
+                    )
                 }
                 IdSignatureProtoType.COMPOSITE_SIGNATURE.id -> {
                     val containerSignature = deserializeIdSignature(input)