streamdata: iterator over known idents

Useful for searching.

Signed-off-by: Yonah <contrib@gensokyo.uk>

streamdata_test.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path"
 	"reflect"
+	"slices"
 	"syscall"
 	"testing"
 	"time"
@@ -301,6 +302,15 @@ func TestChannelAdd(t *testing.T) {
 		t.Errorf("Add: %#v, want %#v", got, wantVOD)
 	}
 
+	var iterErr error
+	idents := slices.Collect(c.All(&iterErr))
+	if iterErr != nil {
+		t.Fatalf("All: error = %#v", iterErr)
+	}
+	if len(idents) != 1 || idents[0].String() != wantIdent {
+		t.Errorf("All: %#v", idents)
+	}
+
 	if gotVOD, err := c.Load(&ident); err != nil {
 		t.Fatalf("Load: error = %v", err)
 	} else if *gotVOD != wantVOD {