Add `strict_shape` option to CheckpointLoader

[Nic-Ma]

Is your feature request related to a problem? Please describe.
Currently, we don't support the transfer-learning case that load a checkpoint with same layer names but different shape.
We can refer to below code:

model_3 = get_model_with_3_classes()
state_dict_model_4 = torch.load("best_model_4.pt")

@trainer.on(Events.STARTED, model_3, state_dict_model_4)
def permissive_model_loader(model, state_dict):
    this_state_dict = model.state_dict()
    matched_state_dict = {
        k: v for k, v in state_dict.items()
        if k in this_state_dict and v.shape == this_state_dict[k].shape
    }
    model.load_state_dict(matched_state_dict, strict=False)

trainer.run(...)

Thanks.