feat(nodes): change intermediates handling

- `ImageType` is now restricted to `results` and `uploads`.
- Add a reserved `meta` field to nodes to hold the `is_intermediate` boolean. We can extend it in the future to support other node `meta`.
- Add a `is_intermediate` column to the `images` table to hold this. (When `latents`, `conditioning` etc are added to the DB, they will also have this column.)
- All nodes default to `*not* intermediate`. Nodes must explicitly be marked `intermediate` for their outputs to be `intermediate`.
- When building a graph, you can set `node.meta.is_intermediate=True` and it will be handled as an intermediate.
- Add a new `update()` method to the `ImageService`, and a route to call it. Updates have a strict model, currently only `session_id` and `image_category` may be updated.
- Add a new `update()` method to the `ImageRecordStorageService` to update the image record using the model.

invokeai/app/invocations/baseinvocation.py

@@ -39,6 +39,12 @@ class BaseInvocationOutput(BaseModel):
         return tuple(subclasses)
 
 
+class InvocationMeta(BaseModel):
+    is_intermediate: bool = Field(
+        default=False,
+        description="Whether this is an intermediate node. Intermediate nodes are periodically deleted."
+    )
+
 class BaseInvocation(ABC, BaseModel):
     """A node to process inputs and produce outputs.
     May use dependency injection in __init__ to receive providers.
@@ -78,6 +84,8 @@ class BaseInvocation(ABC, BaseModel):
     
     #fmt: off
     id: str = Field(description="The id of this node. Must be unique among all nodes.")
+    type: str = Field(description="The type of this node. Must be unique among all nodes.")
+    meta: InvocationMeta = Field(default=InvocationMeta(), description="The meta properties of this node.")
     #fmt: on