Add support for fermi level alignment.

[floatingCatty]

Describe Current Status and Possible Solution

Current Status: The NEGF module now attains a constant fermi-energy input for the device and both leads. This is practical when the system is homogeneous and its size is sufficiently large, but it may fail when with confined systems, and Heterogeneous in leads and devices.

Possible Solutions:

1. We need to define the fermi-energy for devices and leads separately. The tag should be moved from negf's options into its submodule stru_option.
2. Further, a fermi-level alignment method needs to be implemented. Possible references are ASE.transport module.

Additional Context

No response