Remove runner, parallel, engine and device (#2216)

* Remove runner, parallel, engine and device

* fix format

* remove outdated docs

mmcv/runner/hooks/iter_timer.py

-# Copyright (c) OpenMMLab. All rights reserved.
-import time
-
-from .hook import HOOKS, Hook
-
-
-@HOOKS.register_module()
-class IterTimerHook(Hook):
-
-    def before_epoch(self, runner):
-        self.t = time.time()
-
-    def before_iter(self, runner):
-        runner.log_buffer.update({'data_time': time.time() - self.t})
-
-    def after_iter(self, runner):
-        runner.log_buffer.update({'time': time.time() - self.t})
-        self.t = time.time()

mmcv/runner/hooks/logger/__init__.py

-# Copyright (c) OpenMMLab. All rights reserved.
-from .base import LoggerHook
-from .clearml import ClearMLLoggerHook
-from .dvclive import DvcliveLoggerHook
-from .mlflow import MlflowLoggerHook
-from .neptune import NeptuneLoggerHook
-from .pavi import PaviLoggerHook
-from .segmind import SegmindLoggerHook
-from .tensorboard import TensorboardLoggerHook
-from .text import TextLoggerHook
-from .wandb import WandbLoggerHook
-
-__all__ = [
-    'LoggerHook', 'MlflowLoggerHook', 'PaviLoggerHook',
-    'TensorboardLoggerHook', 'TextLoggerHook', 'WandbLoggerHook',
-    'NeptuneLoggerHook', 'DvcliveLoggerHook', 'SegmindLoggerHook',
-    'ClearMLLoggerHook'
-]

mmcv/runner/hooks/memory.py

-# Copyright (c) OpenMMLab. All rights reserved.
-import torch
-
-from .hook import HOOKS, Hook
-
-
-@HOOKS.register_module()
-class EmptyCacheHook(Hook):
-
-    def __init__(self,
-                 before_epoch: bool = False,
-                 after_epoch: bool = True,
-                 after_iter: bool = False):
-        self._before_epoch = before_epoch
-        self._after_epoch = after_epoch
-        self._after_iter = after_iter
-
-    def after_iter(self, runner):
-        if self._after_iter:
-            torch.cuda.empty_cache()
-
-    def before_epoch(self, runner):
-        if self._before_epoch:
-            torch.cuda.empty_cache()
-
-    def after_epoch(self, runner):
-        if self._after_epoch:
-            torch.cuda.empty_cache()