Naming discrepancy between `env` in Processing and `environment` in Estimator

# Describe the feature you'd like
There is a discrepancy on passing environment variables in Processing and Estimator. The parameter is called `env` in Processing and `environment` in Estimator.

I would like these to be aligned. For backwards compatibility sake, this should probably be manifested through a `environment_variables` parameter, but any solution would work for me.

## The problem
The problem is that we cannot have a unified interface to these entities using `**kwargs` to pass arguments without manually parsing a parameter ourselves.

Current situation van be something like this if we use `env` for both situations:

```python
def data_processing(environment: Literal["dev", "preprod", "prod"], **kwargs):
initialize_environment(environment)

return Processing(**kwargs)

def model_training(environment: Literal["dev", "preprod", "prod"], **kwargs):
initialize_environment(environment)

env_vars = kwargs.pop("env")
if env_vars:
kwargs["environment"] = env_vars

return Estimator(**kwargs)

data_processing(environment="dev", env={"MY_VAR": 42})
model_training(environment="dev", env={"MY_VAR": 67})
```

Or with a more compatible interface

```python
def data_processing(environment: Literal["dev", "preprod", "prod"], **kwargs):
initialize_environment(environment)

env_vars = kwargs.pop("environment_variables")
if env_vars:
kwargs["env"] = env_vars

return Processing(**kwargs)

def model_training(environment: Literal["dev", "preprod", "prod"], **kwargs):
initialize_environment(environment)

env_vars = kwargs.pop("environment_variables")
if env_vars:
kwargs["environment"] = env_vars

return Estimator(**kwargs)

data_processing(environment="dev", environment_variables={"MY_VAR": 42})
model_training(environment="dev", environment_variables={"MY_VAR": 67})
```

Ideally, we would want it to look like this because both classes accept a `environment_variables` parameter:

```python
def data_processing(environment: Literal["dev", "preprod", "prod"], **kwargs):
initialize_environment(environment)

return Processing(**kwargs)

def model_training(environment: Literal["dev", "preprod", "prod"], **kwargs):
initialize_environment(environment)

return Estimator(**kwargs)

data_processing(environment="dev", environment_variables={"MY_VAR": 42})
model_training(environment="dev", environment_variables={"MY_VAR": 67})
```

首先定位 Processing 和 Estimator 的入口点及其现有的环境变量参数。比较 `env` 和 `environment` 的暴露方式，然后确定一个向后兼容的共享接口；当两个实体都接受对齐后的参数且不破坏现有用法时，即视为完成。

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