add option to advanced background "As Img Tag"

[nickfmc]

Description

a lot of sites use an image as a banner at the top of the page, this image may have text ontop of the image like the page title. however there are reasons to not use a bg image for this.

1- you want that image to be used by OG as the first image on the page 2- you want to have the image right sized using src-set 3- you have a webp plugin that auto replaces your jpp/png's with webp's dynamically for img tags. 4- you can have an SEO image title and alt tag if this image makes sense to be indexed

What I'd like to see

A option inside the advanced bg you can select "as image tag", that applies position:absolute, object-fit:cover, width: 100%, height:100%

It's easy enough to do this with CSS for your own theme, but for client hand off it wont look nice in the backend currently without major hacky editor-content styles.

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