Add Int support for functional.avg/maxpool

[MARD1NO]

给 nn.functional.avg/maxpool增加 int 传参支持

[github-actions]

Speed stats:

GPU Name: GeForce GTX 1080 

OneFlow resnet50 time: 128.1ms (= 6402.6ms / 50, input_shape=[16, 3, 224, 224])
PyTorch resnet50 time: 138.7ms (= 6933.1ms / 50, input_shape=[16, 3, 224, 224])
Relative speed: 1.08 (= 138.7ms / 128.1ms)

OneFlow resnet50 time: 74.3ms (= 3716.3ms / 50, input_shape=[8, 3, 224, 224])
PyTorch resnet50 time: 81.9ms (= 4097.2ms / 50, input_shape=[8, 3, 224, 224])
Relative speed: 1.10 (= 81.9ms / 74.3ms)

OneFlow resnet50 time: 48.5ms (= 2427.3ms / 50, input_shape=[4, 3, 224, 224])
PyTorch resnet50 time: 56.5ms (= 2825.4ms / 50, input_shape=[4, 3, 224, 224])
Relative speed: 1.16 (= 56.5ms / 48.5ms)

OneFlow resnet50 time: 40.6ms (= 2028.5ms / 50, input_shape=[2, 3, 224, 224])
PyTorch resnet50 time: 48.4ms (= 2417.9ms / 50, input_shape=[2, 3, 224, 224])
Relative speed: 1.19 (= 48.4ms / 40.6ms)

OneFlow resnet50 time: 39.4ms (= 1971.0ms / 50, input_shape=[1, 3, 224, 224])
PyTorch resnet50 time: 40.5ms (= 2023.4ms / 50, input_shape=[1, 3, 224, 224])
Relative speed: 1.03 (= 40.5ms / 39.4ms)

OneFlow resnet50 time: 156.7ms (= 7836.1ms / 50, input_shape=[16, 3, 224, 224], ddp, world size=2)
PyTorch resnet50 time: 159.0ms (= 7947.8ms / 50, input_shape=[16, 3, 224, 224], ddp, world size=2)
Relative speed: 1.01 (= 159.0ms / 156.7ms)

OneFlow resnet50 time: 101.8ms (= 5089.4ms / 50, input_shape=[8, 3, 224, 224], ddp, world size=2)
PyTorch resnet50 time: 101.9ms (= 5093.0ms / 50, input_shape=[8, 3, 224, 224], ddp, world size=2)
Relative speed: 1.00 (= 101.9ms / 101.8ms)

OneFlow resnet50 time: 84.0ms (= 4199.5ms / 50, input_shape=[4, 3, 224, 224], ddp, world size=2)
PyTorch resnet50 time: 84.1ms (= 4206.4ms / 50, input_shape=[4, 3, 224, 224], ddp, world size=2)
Relative speed: 1.00 (= 84.1ms / 84.0ms)

OneFlow resnet50 time: 71.4ms (= 3568.2ms / 50, input_shape=[2, 3, 224, 224], ddp, world size=2)
PyTorch resnet50 time: 66.4ms (= 3318.8ms / 50, input_shape=[2, 3, 224, 224], ddp, world size=2)
Relative speed: 0.93 (= 66.4ms / 71.4ms)

OneFlow resnet50 time: 73.1ms (= 3656.1ms / 50, input_shape=[1, 3, 224, 224], ddp, world size=2)
PyTorch resnet50 time: 61.5ms (= 3074.5ms / 50, input_shape=[1, 3, 224, 224], ddp, world size=2)
Relative speed: 0.84 (= 61.5ms / 73.1ms)