Provide utils/ directory for repo maintenance scripts

Summary:
The scripts/ and config/ directories are going to be deprecated:

• once Vault is ready, config/ files should be instead converted to Jinja templates using a Vault pillar for secrets
• scripts/ should be provided in units

But at this stage, scripts/ also have another content: scripts to ease
the maintenance of this repository. Such scripts should go in utils/.

Test Plan: no op

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1261