feat: add some precommit (#274)

- ensure correct formatting with shfmt
- ensure correct syntax with shellcheck

Co-authored-by: damien cavagnini <damien.cavagnini@corp.ovh.com>

hooks/shellcheck.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+for script in "$@"; do
+    /usr/bin/shellcheck --exclude=SC2317 --color=always --shell=bash -x --source-path=SCRIPTDIR "$script"
+done
+
+exit 0