style: Apply go fmt to go code (#2046)

~I will add pre-commit hook later if I find a good one~

Found a nice repo, but it is no longer maintained:
https://github.com/dnephin/pre-commit-golang
So, I implemented the check as a local hook.

pre-commit-hooks/run-go-fmt.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+#
+# Capture and print stdout, since gofmt doesn't use proper exit codes
+#
+set -e -o pipefail
+
+if ! command -v gofmt &> /dev/null ; then
+    echo "gofmt not installed or available in the PATH" >&2
+    exit 1
+fi
+
+output="$(gofmt -l -w "$@")"
+echo "$output"
+[[ -z "$output" ]]