feat: add optional response images with cloudinary

[artis3n]

I was trying to adapt this to this theme and didn't see another option already available, so I thought you might like this PR. Let me know if this isn't the type of change you want to include in the theme.

This optionally provides a capability for responsive images via Cloudinary. It requires images to be hosted in Cloudinary (I have a free account for my blog). It does not add any weight if someone does not wish to use the feature. If they would like to use this, uncommenting cloudinary_cloud_name will load in the necessary javascript.

I am using it like this on my markdown articles:

Notably, the src path is the remote path in Cloudinary where my image is located, not a local path. This cloudinary configuration will also auto-select the best image type for the user's browser - e.g. AVIF or webp if supported, else png, jpg, etc. So a file extension is excluded from the path in my example.

The new meta tag addition to head.html is to gather mobile device dimensions so images can be properly sized in those cases.

[gurusabarish]

Thanks for the pull request @artis3n ❤️

[artis3n]

Thanks! Working through customizations I'm making on my site that require updates to the head or scripts template, so getting them into the theme where I can :)