Feature Request - Add ability to set environment variables and command-line flags for Cloud SQL Auth Proxy in Cloud Code

### Description:
Currently, the Cloud Code plugin for Cloud SQL Auth Proxy does not provide a way to pass environment variables or command-line flags to the `cloud-sql-proxy` command. This makes it difficult to customize the behavior of cloud-sql-proxy for different use cases. For example, when using automatic authentication with IAM credentials, the `--auto-iam-authn` flags cannot be set.

## Expected Behavior:
Cloud Code should provide an option to set environment variables and command-line flags for the cloud-sql-proxy command when using Cloud SQL Auth Proxy.

## Actual Behavior:
Cloud Code does not provide an option to set environment variables or command-line flags for the cloud-sql-proxy command when using Cloud SQL Auth Proxy.

## Environment:
Cloud Code version: 23.5.1-222-IB.1
Cloud SDK:
- Are you allowing the plugin to manage the Cloud SDK: YES (Actually tried with both settings, the issue is there anyway)
- Version of the Cloud SDK: 430.0.0

IDE: PyCharm 2023.1.1 (Professional Edition)
Cloud SQL Auth Proxy version installed by Cloud Code: 2.0.0-preview.3
Cloud SQL Auth Proxy version installed manually: 2.2.0
OS: Linux (Manjaro Linux, kernel 6.3)