Cover image inline CSS should use esc_url_raw() instead of esc_url() to escape attachment path.

[DJPaul]

The & character in a chained set of query parameters was being escaped. I discovered this while implementing support for a Photon-like service.

[djpaul]

In 10643:

Attachments: when rendering inline CSS for cover images, use esc_url_raw to escape the image path.

This prevents entities such as & being decoded into &#038, which can break image URLs that rely on querystring parameters for functionality.

Fixes #6952

[djpaul]

In 10644:

Attachments: when rendering inline CSS for cover images, use esc_url_raw to escape the image path.

This prevents entities such as & being decoded into &#038, which can break image URLs that rely on querystring parameters for functionality.

Fixes #6952 (2.5 branch)