[python-package] Lint code locally before pushing changes to remote

[TremaMiguel]

Summary

Create a Makefile that lints code locally before pushing changes to remote.

make lint-python

this will run code inside test.sh

echo "Linting Python code"
    pycodestyle --ignore=E501,W503 --exclude=./.nuget,./external_libs . || exit -1
    pydocstyle --convention=numpy --add-ignore=D105 --match-dir="^(?!^external_libs|test|example).*" --match="(?!^test_|setup).*\.py" . || exit -1
    isort . --check-only || exit -1
    mypy --ignore-missing-imports python-package/ || true

Motivation

LightGBM contributors might wait several attempts until the ci lint stage passes correctly, with the local make command he/she lint the changes locally before submitting it to review.

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