feat: new helpers and masking/encrypting attributes

New helper functions were added to make call-site less likely to need
to pull `go.opentelemetry.io/otel/attribute` as a dependency.
Additionally `Encrypted` and `Masked` were added to add a possibility of
logging sensitive data in a more secure manner.

example/main.go

@@ -8,6 +8,7 @@ import (
 	"os/signal"
 	"time"
 
+	"git.ma-al.com/maal-libraries/observer/pkg/attr"
 	"git.ma-al.com/maal-libraries/observer/pkg/attr/layer_attr"
 	"git.ma-al.com/maal-libraries/observer/pkg/event"
 	"git.ma-al.com/maal-libraries/observer/pkg/exporters"
@@ -111,6 +112,11 @@ func Serv(ctx context.Context) *fiber.Error {
 		return fiber.NewError(500, "xd")
 	}
 
+	span.SetAttributes(
+		attr.Masked("some_masked_value", "some_masked_value"),
+		attr.Encrypted("some_encrypted_value", "some_encrypted_value"),
+	)
+
 	return fiber.NewError(500, "x")
 }