Prerequisites

• I have added steps to test this contribution in the description below

Description

This PR introduces blueprint containers (folders) for explicitly organizing blueprints in a tree, rather than the current virtual (fake) structure by content type.

As part of the migration to V14, all existing blueprints will be moved into containers named by their content type, thus mimicking the structure that is today.

Testing this PR

Create a V13 site with blueprints (or reach out to @kjac for a test DB):

Upgrade the V13 database to V14, then use the API to verify that the blueprints have been moved into containers:

Now test that:

• New blueprints can be created in containers.
• Existing blueprints can be moved between containers.
• Existing blueprints can be moved to and from the tree root.
• New containers can be created.
• Existing containers can be renamed.0
• Containers can not be moved to other containers.
• Containers can not be deleted if they are not empty.
• The blueprint items endpoint supports container items too.
• Containers are listed before blueprints in the tree endpoints, and pagination works across both types.

Limitations of this PR

This PR does not support creating blueprints from existing content in a container. We need to work out the client-side details of this feature before we implement the APIs to support it.