Marketplace Configuration Enablement

[obstropolos]

We want to make it so that someone launching OpenMinter is able to accurately configure what they wish to be available in the marketplace in their instance. In this case, the admin would be choosing which contracts are included in their instance, or it would include any of their originated contracts.

Journey

• Launch and configure own instance of OpenMinter
• Marketplace page by default has no listed assets but instead an "enable marketplace" button that displays a number of toggles
• The launching party has the ability to include the base minter contract if they do wish to
• The launching party is then able to select either already-existing contracts that they've created, or an option that enables the marketplace to pick up on any of their owned contracts
• Once launched, visitors are able to see assets for sale only from those specific contracts, and if the instance allows open creation of assets, those cannot be included in the marketplace if they're made in a non-designated contract.

[obstropolos]

Initial version handled via #406 with release of v0.7.0 - additional options and improvements to occur in later releases.