Cloudinary Stream Wrapper caches items in the database (Database Storage) but never actually checks if an item is inside the storage

Problem/Motivation

The Cloudinary plugin writes items after retrieving them from the API to the database storage. But it will never check if the item is inside the DB storage when retrieving them. For pages that only have 1-2 images at most, you will not notice the issue directly but if we have a page with a vast collection it can take over 40 seconds (800ms - 1s per image) for a page to render and load.

Steps to reproduce

Clean install the plugin (2.1.3), and retrieve on a page a huge amount of images, the more the better the result. You will notice an increase in page load when the amount of images increases that are loaded through Cloudinary.

Proposed resolution

The cloudinary_stream_wrapper_resource_prepare code is never called anywhere within the module causing every request for an API call.

Partial patch that resolves this issue with cloudinary_stream_wrapper_load_file, The page I used locally to test took 43 seconds to load before applying the patch and afterward 430ms.

Remaining tasks

Probably still needs additional checks for folders and other options. This was just in our use case the only call necessary to have high performance.

User interface changes

n/a

API changes

n/a

Data model changes

n/a