[booster] added the accelerator implementation (#3159)

tests/test_booster/test_accelerator.py

@@ -0,0 +1,13 @@
+import pytest
+import torch.nn as nn
+from torchvision.models import resnet18
+
+from colossalai.booster.accelerator import Accelerator
+
+
+@pytest.mark.parametrize('device', ['cpu', 'cuda'])
+def test_accelerator(device):
+    acceleartor = Accelerator(device)
+    model = nn.Linear(8, 8)
+    model = acceleartor.configure_model(model)
+    assert next(model.parameters()).device.type == device