[WIP] Add UI to invalidate cache for individual images from WordPress

[Codex]

Thanks for asking me to work on this. I will get started on it and keep this PR's description up to date as I form a plan and make progress.

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This section details on the original issue you should resolve

<issue_title>Add UI to invalidate cache for individual images directly from WordPress</issue_title>
<issue_description>### Problem
Currently, when a user wants to clear the cache for a specific updated image from the WordPress dashboard, their only option is to regenerate the entire Optimole image cache. Flushing the entire cache for a single image update is highly inefficient and disruptive for high-traffic sites. While there is an API available to invalidate specific assets, it is inaccessible to non-technical WP admins.

Desired Behavior

Provide a setting or action within the WordPress dashboard to dump the cache for a single image or a small selection of images. This could be exposed as a bulk action/row action in the native WP Media Library or an input field in the Optimole settings where an admin can paste specific URLs to clear.

Acceptance Criteria

• Provide a UI control within the WordPress admin (e.g., in Media Library and/or Optimole settings) to trigger cache invalidation for specific images.
• The action securely triggers the existing POST /api/optml/v2/cache/invalidate/asset backend endpoint using the site's API credentials.
• An admin notice clearly confirms whether the single-image cache was successfully refreshed or if it failed.

Customer Context

An agency partner managing high-traffic sites requests a targeted way to clear cache for individual images via the WordPress backend. Regenerating the entire cache is too heavy-handed, and their team cannot easily use the Optimole REST API.

https://secure.helpscout.net/conversation/3293257808/487980</issue_description>

<agent_instructions>Add this feature in the media page in list and grid mode as a shortcut link, like how offload to Optimole quick link is present</agent_instructions>

Comments on the Issue (you are @codex[agent] in this section)