Import buildifier

This patch sets up buildifier to run as part of CI. It can also be run
manually via `//tools/lint:buildifier`.

As a consequence, I needed to make the whole repo conform.

Signed-off-by: Philipp Schrader <philipp.schrader@gmail.com>
Change-Id: Ic41c97b17255813b6c21aef40ab2f8a216683a2c
diff --git a/y2021_bot3/BUILD b/y2021_bot3/BUILD
index f068dbe..07429e0 100644
--- a/y2021_bot3/BUILD
+++ b/y2021_bot3/BUILD
@@ -1,7 +1,5 @@
 load("//frc971:downloader.bzl", "robot_downloader")
 load("//aos:config.bzl", "aos_config")
-load("@com_google_protobuf//:protobuf.bzl", "cc_proto_library")
-load("@com_github_google_flatbuffers//:build_defs.bzl", "flatbuffer_cc_library")
 
 robot_downloader(
     data = [
diff --git a/y2021_bot3/control_loops/drivetrain/BUILD b/y2021_bot3/control_loops/drivetrain/BUILD
index 2741fd2..3f9a3df 100644
--- a/y2021_bot3/control_loops/drivetrain/BUILD
+++ b/y2021_bot3/control_loops/drivetrain/BUILD
@@ -1,6 +1,3 @@
-load("@com_github_google_flatbuffers//:build_defs.bzl", "flatbuffer_cc_library")
-load("//tools/build_rules:select.bzl", "compiler_select", "cpu_select")
-
 genrule(
     name = "genrule_drivetrain",
     outs = [
diff --git a/y2021_bot3/control_loops/superstructure/BUILD b/y2021_bot3/control_loops/superstructure/BUILD
index d1d2684..c6b36a1 100644
--- a/y2021_bot3/control_loops/superstructure/BUILD
+++ b/y2021_bot3/control_loops/superstructure/BUILD
@@ -1,8 +1,8 @@
-package(default_visibility = ["//visibility:public"])
-
 load("@com_github_google_flatbuffers//:build_defs.bzl", "flatbuffer_cc_library")
 load("@npm_bazel_typescript//:defs.bzl", "ts_library")
 
+package(default_visibility = ["//visibility:public"])
+
 flatbuffer_cc_library(
     name = "superstructure_goal_fbs",
     srcs = [