feat: add 2 weight functions in multi-label

[thsno02]

根据 https://github.com/PaddlePaddle/PaddleClas/issues/2951 新增两个 ratio2weight 函数。代码里延续论文中的命名，所以原 ratios2weight 改为 ratios2weight_1。

Type 3 示例：

# loss function config for traing/eval process
Loss:
  Train:
    - MultiLabelLoss:
        weight: 1.0
        weight_type: 3 
        weight_alpha: 1 # float
        weight_ratio: True
        size_sum: True
  Eval:
    - MultiLabelLoss:
        weight: 1.0
        weight_type: 3 
        weight_alpha: 1 # float
        weight_ratio: True
        size_sum: True

Type 2/1 示例：

# loss function config for traing/eval process
Loss:
  Train:
    - MultiLabelLoss:
        weight: 1.0
        weight_type: 2 
        weight_ratio: True
        size_sum: True
  Eval:
    - MultiLabelLoss:
        weight: 1.0
        weight_type: 2
        weight_ratio: True
        size_sum: True

但是 https://github.com/PaddlePaddle/PaddleClas/blob/release/2.5/ppcls/loss/dmlloss.py 中 import 了 ratio2weight 这个函数，目前的解决方案是在 dmlloss 中开启 weight_type 和 weight_alpha 这两个参数，与 multilabelloss 中保持一致，然后计算对应的 loss。

[paddle-bot[bot]]

Thanks for your contribution!