Clean up import statements

[Changmin Choi]

Need to rewrite import statements in this order

import PythonOriginPackage
from PythonOriginPackage import foo

import ThirdPartyPackage
from ThirdPartyPackage import foo

import OwnModule
from OwnModule import foo

[Changmin Choi]

formatted with isort / added isort to CI / installed isort to pre-commit