Support Code128 auto-detection

RFC @jamesbrink (and any interested parties) — This PR removes support for `code-128a`, `code-128b`, and `code-128c` in favor of `code-128` which handles auto-detection and supports multiple subsets within a single barcode.

This requires at least Barby 0.6.0.

In order to support for multiple subset barcodes I needed to add support for escaping/unescaping URIs, something we should have done originally — oops!