Re-add prefix parameter on cleanupIds to fix unique ids

[yoriiis]

Fixed: #1746

SVGO v3.0.0 removed the prefix parameter in the cleanupIds plugin in favor of prefixIds plugin. This created a regression with id conflicts with multiple SVGs.

The PR propose a revert of the bc07c48 commit to re-add the parameter and let user add a prefix with a custom hash.

Exemple implementation to resolve the id conflicts.

const crypto = require('crypto');

module.exports = {
    plugins: [
        {
            name: 'preset-default',
            params: {
                overrides: {
                    cleanupIDs: {
                        prefix: {
                            toString() {
                                return crypto.randomBytes(20).toString('hex').slice(0, 4);
                            }
                        }
                    }
                }
            }
        }
    ]
}

[yoriiis]

@TrySound and @GreLI could you take a look to this PR please? Thanks 🙏

[PurpleTape]

Any updates? 🥺🥺🥺

[yoriiis]

FYI @SethFalco

[SethFalco]

@yoriiis I'm working on improving our documentation. As soon as I'm done with that, I'll give this a look!

While reviewing this, I want to check out the prefixIds plugin and see if we can solve the issue there, rather than maintain the functionality twice or merge the plugins again, though.

One obvious bug I can see in Prefix IDs already, the plugin modifies IDs and references to IDs separately. It'll always break vectors when a function with random output is passed. I'd rather fix prefixIds than add this back to cleanupIds.

The prefixIds plugin should probably store a map of IDs that have been modified by the plugin, so if it encounters an ID again, it can take the previously generated one from the map instead.

Regarding docs, you can see progress here:
https://svgo.dev/docs/plugins/cleanupIds/