Add ability to instantiatate blueprints via metamodels

### Is your feature request related to a problem?

Currently, `metaaplyblueprint` allows applying already **instantiated** blueprints.

However, I have a different use case (related to #18161).

I would like to manage multiple blueprints from a single "main" one. The way I imagine this is to have something like this:

```yaml
version: 1
metadata:
name: Main blueprint
entries:
- model: authentik_blueprints.metaapplyblueprint # or different metamodel
attrs:
required: true # require `path` to be valid but create a new blueprint instance if one doesn't exist
path: oci://registry.com/my/blueprint/1
context: {...} # this for example creates a flow with certain settings (see #18161)
...
...
... # more entries
```

### Describe the solution you'd like

Have the ability to create new blueprint instances via metamodels

### Describe alternatives that you've considered

Load an instance of all blueprints manually first, then apply them via `metaaplyblueprint` with different contexts (see #18161).

### Additional context

_No response_