isort: Have better configuration
isort: Have better configuration

Add pip._vendor as a third party package
Use the indentation style that the project uses
Add pip and tests as a known first party packages
Change default section to THIRDPARTY

rouge8/pip,xavfernandez/pip,pfmoore/pip,rouge8/pip,pradyunsg/pip,rouge8/pip,sbidoul/pip,pfmoore/pip,zvezdan/pip,RonnyPfannschmidt/pip,RonnyPfannschmidt/pip,RonnyPfannschmidt/pip,pradyunsg/pip,zvezdan/pip,xavfernandez/pip,xavfernandez/pip,techtonik/pip,techtonik/pip,sbidoul/pip,techtonik/pip,zvezdan/pip,pypa/pip,pypa/pip