AWS requires Interface to be specified when using elasticIP

## Feature Request

When setting an elastic IP for an AWS instance that is using multiple interfaces you must specify the interface you wish to use with the elasticIP.

Currently the method does not allow you to specify the interface: ex_associate_address_with_node(node, elastic_ip).

I propose adding an optional parameter to this function that would allow you to define the interface.

Such as: ex_associate_address_with_node(node, elastic_ip, interface).

首先在 Python provider 实现中定位 ex_associate_address_with_node，并检查当前如何请求关联 elastic IP。跟踪用于选择接口的 AWS API 参数，然后更新相关测试以覆盖可选的接口参数。完成的标准是现有的双参数调用仍然有效，并且调用方可以将 elastic IP 关联到选定的接口。

由索引模型根据 Issue 内容生成。