lint: api: sort imports

After configuring sort behavior in isort.cfg, run `./scripts/isort`
on all the api/ modules in the tree.

BUG=b:187788732
TEST=`cros lint` is clean

Change-Id: I838009ea70ff52a1560a597509909c0b514247b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/3615052
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Reviewed-by: Alex Klein <saklein@chromium.org>
diff --git a/api/compile_build_api_proto_unittest.py b/api/compile_build_api_proto_unittest.py
index 751fcf4..9420252 100644
--- a/api/compile_build_api_proto_unittest.py
+++ b/api/compile_build_api_proto_unittest.py
@@ -5,6 +5,7 @@
 """compile_build_api_proto tests."""
 
 from chromite.third_party.google import protobuf
+
 from chromite.api import compile_build_api_proto