Refactor import statements in nodes_train.py

Reorganized and cleaned up import statements, removing unused imports and adding specific module imports for better clarity and organization.

comfy_extras/nodes_train.py

@@ -1,8 +1,8 @@
 import datetime
 import json
+import logging
 import math
 import os
-import logging
 
 import numpy as np
 import safetensors
@@ -10,13 +10,15 @@ import torch
 from PIL import Image, ImageDraw, ImageFont
 from PIL.PngImagePlugin import PngInfo
 
-import comfy
-import comfy_extras
+import comfy.samplers
+import comfy.utils
+import comfy_extras.nodes_custom_sampler
 import folder_paths
 import node_helpers
 from comfy.cli_args import args
 from comfy.comfy_types.node_typing import IO
 
+
 class TrainSampler(comfy.samplers.Sampler):
 
     def __init__(self, loss_fn, optimizer, loss_callback=None):