make model manager v2 ready for PR review

- Replace legacy model manager service with the v2 manager.

- Update invocations to use new load interface.

- Fixed many but not all type checking errors in the invocations. Most
  were unrelated to model manager

- Updated routes. All the new routes live under the route tag
  `model_manager_v2`. To avoid confusion with the old routes,
  they have the URL prefix `/api/v2/models`. The old routes
  have been de-registered.

- Added a pytest for the loader.

- Updated documentation in contributing/MODEL_MANAGER.md

invokeai/app/services/model_manager/model_manager_base.py

@@ -2,9 +2,10 @@
 
 from abc import ABC, abstractmethod
 
-from pydantic import BaseModel, Field
 from typing_extensions import Self
 
+from invokeai.app.services.invoker import Invoker
+
 from ..config import InvokeAIAppConfig
 from ..download import DownloadQueueServiceBase
 from ..events.events_base import EventServiceBase
@@ -14,12 +15,13 @@ from ..model_records import ModelRecordServiceBase
 from ..shared.sqlite.sqlite_database import SqliteDatabase
 
 
-class ModelManagerServiceBase(BaseModel, ABC):
+class ModelManagerServiceBase(ABC):
     """Abstract base class for the model manager service."""
 
-    store: ModelRecordServiceBase = Field(description="An instance of the model record configuration service.")
-    install: ModelInstallServiceBase = Field(description="An instance of the model install service.")
-    load: ModelLoadServiceBase = Field(description="An instance of the model load service.")
+    # attributes:
+    # store: ModelRecordServiceBase = Field(description="An instance of the model record configuration service.")
+    # install: ModelInstallServiceBase = Field(description="An instance of the model install service.")
+    # load: ModelLoadServiceBase = Field(description="An instance of the model load service.")
 
     @classmethod
     @abstractmethod
@@ -37,3 +39,29 @@ class ModelManagerServiceBase(BaseModel, ABC):
         method simplifies the construction considerably.
         """
         pass
+
+    @property
+    @abstractmethod
+    def store(self) -> ModelRecordServiceBase:
+        """Return the ModelRecordServiceBase used to store and retrieve configuration records."""
+        pass
+
+    @property
+    @abstractmethod
+    def load(self) -> ModelLoadServiceBase:
+        """Return the ModelLoadServiceBase used to load models from their configuration records."""
+        pass
+
+    @property
+    @abstractmethod
+    def install(self) -> ModelInstallServiceBase:
+        """Return the ModelInstallServiceBase used to download and manipulate model files."""
+        pass
+
+    @abstractmethod
+    def start(self, invoker: Invoker) -> None:
+        pass
+
+    @abstractmethod
+    def stop(self, invoker: Invoker) -> None:
+        pass

invokeai/app/services/model_manager/model_manager_default.py

@@ -3,6 +3,7 @@
 
 from typing_extensions import Self
 
+from invokeai.app.services.invoker import Invoker
 from invokeai.backend.model_manager.load import ModelCache, ModelConvertCache
 from invokeai.backend.model_manager.metadata import ModelMetadataStore
 from invokeai.backend.util.logging import InvokeAILogger
@@ -10,9 +11,9 @@ from invokeai.backend.util.logging import InvokeAILogger
 from ..config import InvokeAIAppConfig
 from ..download import DownloadQueueServiceBase
 from ..events.events_base import EventServiceBase
-from ..model_install import ModelInstallService
-from ..model_load import ModelLoadService
-from ..model_records import ModelRecordServiceSQL
+from ..model_install import ModelInstallService, ModelInstallServiceBase
+from ..model_load import ModelLoadService, ModelLoadServiceBase
+from ..model_records import ModelRecordServiceBase, ModelRecordServiceSQL
 from ..shared.sqlite.sqlite_database import SqliteDatabase
 from .model_manager_base import ModelManagerServiceBase
 
@@ -27,6 +28,38 @@ class ModelManagerService(ModelManagerServiceBase):
     model_manager.load    -- Routines to load models into memory.
     """
 
+    def __init__(
+        self,
+        store: ModelRecordServiceBase,
+        install: ModelInstallServiceBase,
+        load: ModelLoadServiceBase,
+    ):
+        self._store = store
+        self._install = install
+        self._load = load
+
+    @property
+    def store(self) -> ModelRecordServiceBase:
+        return self._store
+
+    @property
+    def install(self) -> ModelInstallServiceBase:
+        return self._install
+
+    @property
+    def load(self) -> ModelLoadServiceBase:
+        return self._load
+
+    def start(self, invoker: Invoker) -> None:
+        for service in [self._store, self._install, self._load]:
+            if hasattr(service, "start"):
+                service.start(invoker)
+
+    def stop(self, invoker: Invoker) -> None:
+        for service in [self._store, self._install, self._load]:
+            if hasattr(service, "stop"):
+                service.stop(invoker)
+
     @classmethod
     def build_model_manager(
         cls,