[nodes] Add subgraph library, subgraph usage in CLI, and fix subgraph execution (#3180)

* Add latent to latent (img2img equivalent)
Fix a CLI bug with multiple links per node

* Using "latents" instead of "latent"

* [nodes] In-progress implementation of graph library

* Add linking to CLI for graph nodes (still broken)

* Fix subgraph execution, fix subgraph linking in CLI

* Fix LatentsToLatents

invokeai/app/api/dependencies.py

@@ -3,12 +3,14 @@
 import os
 from argparse import Namespace
 
+from ..services.default_graphs import create_system_graphs
+
 from ..services.latent_storage import DiskLatentsStorage, ForwardCacheLatentsStorage
 
 from ...backend import Globals
 from ..services.model_manager_initializer import get_model_manager
 from ..services.restoration_services import RestorationServices
-from ..services.graph import GraphExecutionState
+from ..services.graph import GraphExecutionState, LibraryGraph
 from ..services.image_storage import DiskImageStorage
 from ..services.invocation_queue import MemoryInvocationQueue
 from ..services.invocation_services import InvocationServices
@@ -69,6 +71,9 @@ class ApiDependencies:
             latents=latents,
             images=images,
             queue=MemoryInvocationQueue(),
+            graph_library=SqliteItemStorage[LibraryGraph](
+                filename=db_location, table_name="graphs"
+            ),
             graph_execution_manager=SqliteItemStorage[GraphExecutionState](
                 filename=db_location, table_name="graph_executions"
             ),
@@ -76,6 +81,8 @@ class ApiDependencies:
             restoration=RestorationServices(config),
         )
 
+        create_system_graphs(services.graph_library)
+
         ApiDependencies.invoker = Invoker(services)
 
     @staticmethod