[PH-5] Predefine environment variables before starting jupyter notebook

[huaichehuang]

Path

• User portal → Notebooks → Start My Server

Result

• Let the user predefine the environment variables they want to pass to the jupyter notebook server.
• The content of the environment variables must be hidden by default due to security reasons. (Like typing password)
• The predefined environment variables can be checked from the notebook server page after the notebook server is started.
• The content of the environment variables on the notebook server page must be hidden by default due to security reasons but can be unhidden by the user.