[git_cl] Organize imports

Separate stdlib and depot_tools, and from imports

Change-Id: I88e40ca07215d918d1354472d9d16c6babef54d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5691997
Commit-Queue: Allen Li <ayatane@chromium.org>
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>

git_cl.py

@@ -32,7 +32,6 @@ import uuid
 import webbrowser
 import zlib
 
-from third_party import colorama
 from typing import Any
 from typing import List
 from typing import Mapping
@@ -40,6 +39,7 @@ from typing import NoReturn
 from typing import Optional
 from typing import Sequence
 from typing import Tuple
+
 import auth
 import clang_format
 import gclient_paths
@@ -65,6 +65,8 @@ import subprocess2
 import swift_format
 import watchlists
 
+from third_party import colorama
+
 
 __version__ = '2.0'