Support for custom Eloquent route keys

[arondeparon]

Description

Laravel has the ability to return a value other than id as the route key name using the getRouteKeyName method on an Eloquent model. (See https://laravel.com/docs/7.x/routing#implicit-binding)

This is useful, if you would like to refer to models by their UUID instead of id, for example.

Ziggy currently has the ability to feed an object to the route() helper, which will automatically access object.id if it is present so that the route will autotically receive this argument as well.

Suggestion

It would be great if there were some way to check the return value of getRouteKeyName() to determine the route key that is needed to fulfil the route expectations, instead of referring to .id.

[bakerkretzmar]

This is a really cool idea, feels like an extension of #307. One thing I'm hesitant about is that right now Ziggy doesn't actually know when something is a 'model', it's just naively checking for an id key on the object. I would want to make sure that if the route key name is something pretty generic like slug, it doesn't accidentally apply to other routes using different model bindings if we pass an object that also has that key.

Also, I suspect it might be hard to get the route key name info, I'm not certain when it's resolved but if it's not available until the request is being handled, that's probably too late for Ziggy.

Would love to see a PR for this! And otherwise I'll take a stab at it when I have time 😊