Add a warning/error for non-standard config sections to improve the awareness of potential sec. issues

[pkarw]

This would be super-useful because of: https://headless-security.org/vsf-best-practices.html#config-file-is-public

I can imagine we're notifying the user about all custom section they've got (especially for vue-storefront) in order to make sure they're not containing any sensitive information.

This PR could be a pretty useful foundation for this feature: vuestorefront/vue-storefront#3212

It's never been merged however it provides you with guidance on all the sections that are supported by VSF as of for Sep 2019 ;P

[jissereitsma]

But why was it never merged? If PR 3212 could be merged anyway, I would be happy to take a look at integrating this in a VSF-based check, so that you can validate the configuration within the VSF PWA using yarn validate or something similar.

The reason I created this specific repository was to validate mainly configuration options that require Magento logic to properly validate: Like a check on Store View codes, product attributes, etcetera.

So I think a security validation would be making more sense in the PWA itself, then in a third party tool that nobody might use :)