feat(nodes): move all invocation metadata (type, title, tags, category) to decorator

All invocation metadata (type, title, tags and category) are now defined in decorators.

The decorators add the `type: Literal["invocation_type"]: "invocation_type"` field to the invocation.

Category is a new invocation metadata, but it is not used by the frontend just yet.

- `@invocation()` decorator for invocations

```py
@invocation(
    "sdxl_compel_prompt",
    title="SDXL Prompt",
    tags=["sdxl", "compel", "prompt"],
    category="conditioning",
)
class SDXLCompelPromptInvocation(BaseInvocation, SDXLPromptInvocationBase):
    ...
```

- `@invocation_output()` decorator for invocation outputs

```py
@invocation_output("clip_skip_output")
class ClipSkipInvocationOutput(BaseInvocationOutput):
    ...
```

- update invocation docs
- add category to decorator
- regen frontend types

tests/nodes/test_nodes.py

@@ -1,65 +1,63 @@
-from typing import Any, Callable, Literal, Union
+from typing import Any, Callable, Union
 from pydantic import Field
-from invokeai.app.invocations.baseinvocation import BaseInvocation, BaseInvocationOutput, InvocationContext
+from invokeai.app.invocations.baseinvocation import (
+    BaseInvocation,
+    BaseInvocationOutput,
+    InvocationContext,
+    invocation,
+    invocation_output,
+)
 from invokeai.app.invocations.image import ImageField
 
 
 # Define test invocations before importing anything that uses invocations
+@invocation_output("test_list_output")
 class ListPassThroughInvocationOutput(BaseInvocationOutput):
-    type: Literal["test_list_output"] = "test_list_output"
-
     collection: list[ImageField] = Field(default_factory=list)
 
 
+@invocation("test_list")
 class ListPassThroughInvocation(BaseInvocation):
-    type: Literal["test_list"] = "test_list"
-
     collection: list[ImageField] = Field(default_factory=list)
 
     def invoke(self, context: InvocationContext) -> ListPassThroughInvocationOutput:
         return ListPassThroughInvocationOutput(collection=self.collection)
 
 
+@invocation_output("test_prompt_output")
 class PromptTestInvocationOutput(BaseInvocationOutput):
-    type: Literal["test_prompt_output"] = "test_prompt_output"
-
     prompt: str = Field(default="")
 
 
+@invocation("test_prompt")
 class PromptTestInvocation(BaseInvocation):
-    type: Literal["test_prompt"] = "test_prompt"
-
     prompt: str = Field(default="")
 
     def invoke(self, context: InvocationContext) -> PromptTestInvocationOutput:
         return PromptTestInvocationOutput(prompt=self.prompt)
 
 
+@invocation("test_error")
 class ErrorInvocation(BaseInvocation):
-    type: Literal["test_error"] = "test_error"
-
     def invoke(self, context: InvocationContext) -> PromptTestInvocationOutput:
         raise Exception("This invocation is supposed to fail")
 
 
+@invocation_output("test_image_output")
 class ImageTestInvocationOutput(BaseInvocationOutput):
-    type: Literal["test_image_output"] = "test_image_output"
-
     image: ImageField = Field()
 
 
+@invocation("test_text_to_image")
 class TextToImageTestInvocation(BaseInvocation):
-    type: Literal["test_text_to_image"] = "test_text_to_image"
-
     prompt: str = Field(default="")
 
     def invoke(self, context: InvocationContext) -> ImageTestInvocationOutput:
         return ImageTestInvocationOutput(image=ImageField(image_name=self.id))
 
 
+@invocation("test_image_to_image")
 class ImageToImageTestInvocation(BaseInvocation):
-    type: Literal["test_image_to_image"] = "test_image_to_image"
-
     prompt: str = Field(default="")
     image: Union[ImageField, None] = Field(default=None)
 
@@ -67,13 +65,13 @@ class ImageToImageTestInvocation(BaseInvocation):
         return ImageTestInvocationOutput(image=ImageField(image_name=self.id))
 
 
+@invocation_output("test_prompt_collection_output")
 class PromptCollectionTestInvocationOutput(BaseInvocationOutput):
-    type: Literal["test_prompt_collection_output"] = "test_prompt_collection_output"
     collection: list[str] = Field(default_factory=list)
 
 
+@invocation("test_prompt_collection")
 class PromptCollectionTestInvocation(BaseInvocation):
-    type: Literal["test_prompt_collection"] = "test_prompt_collection"
     collection: list[str] = Field()
 
     def invoke(self, context: InvocationContext) -> PromptCollectionTestInvocationOutput: