Product & Variant visibility

[michaelbromley]

There should be a flag which allows a Product or ProductVariant to be made invisible in the front-end.

To view hidden products, there could be an extra option flag in the list options input / search input.
Since only admin should be able to view hidden entities, there must exist some logic which checks the user permissions before returning hidden results. Perhaps an error should be thrown if the flag is set to true when the user lacks sufficient permissions.

[michaelbromley]

Notes

Now that we have a separate API for shop & admin, this simplifies how we treat invisible products - simply filter them out for the shop API.

Also we can rename the concept to "enabled" rather than "visible".

Disabling a product or variant implies that it must also be removed from the search index and from any collections to which it belongs.