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

invokeai/app/invocations/upscale.py

@@ -11,7 +11,7 @@ from invokeai.app.invocations.primitives import ImageField, ImageOutput
 
 from invokeai.app.models.image import ImageCategory, ResourceOrigin
 
-from .baseinvocation import BaseInvocation, InputField, InvocationContext, title, tags
+from .baseinvocation import BaseInvocation, InputField, InvocationContext, invocation
 
 # TODO: Populate this from disk?
 # TODO: Use model manager to load?
@@ -23,14 +23,10 @@ ESRGAN_MODELS = Literal[
 ]
 
 
-@title("Upscale (RealESRGAN)")
-@tags("esrgan", "upscale")
+@invocation("esrgan", title="Upscale (RealESRGAN)", tags=["esrgan", "upscale"], category="esrgan")
 class ESRGANInvocation(BaseInvocation):
     """Upscales an image using RealESRGAN."""
 
-    type: Literal["esrgan"] = "esrgan"
-
-    # Inputs
     image: ImageField = InputField(description="The input image")
     model_name: ESRGAN_MODELS = InputField(default="RealESRGAN_x4plus.pth", description="The Real-ESRGAN model to use")