[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/services/invocation_services.py

@@ -19,6 +19,7 @@ class InvocationServices:
     restoration: RestorationServices
 
     # NOTE: we must forward-declare any types that include invocations, since invocations can use services
+    graph_library: ItemStorageABC["LibraryGraph"]
     graph_execution_manager: ItemStorageABC["GraphExecutionState"]
     processor: "InvocationProcessorABC"
 
@@ -29,6 +30,7 @@ class InvocationServices:
             latents: LatentsStorageBase,
             images: ImageStorageBase,
             queue: InvocationQueueABC,
+            graph_library: ItemStorageABC["LibraryGraph"],
             graph_execution_manager: ItemStorageABC["GraphExecutionState"],
             processor: "InvocationProcessorABC",
             restoration: RestorationServices,
@@ -38,6 +40,7 @@ class InvocationServices:
         self.latents = latents
         self.images = images
         self.queue = queue
+        self.graph_library = graph_library
         self.graph_execution_manager = graph_execution_manager
         self.processor = processor
         self.restoration = restoration