Capture spans for `PerformanceElementTiming`

[timfish]

Problem Statement

https://developer.mozilla.org/en-US/docs/Web/API/PerformanceElementTiming

The PerformanceElementTiming interface contains render timing information for image and text node elements the developer annotated with an elementtiming attribute for observation.

The aim of the Element Timing API is to give web developers or analytics tools the ability to measure rendering timestamps of critical elements on a page.

The API supports timing information on the following elements:

• <img> elements,
• <image> elements inside an > > ,
• <video> elements,
• elements which have a contentful background-image property with a URL value for a resource that is actually available,
• groups of text nodes, such as a <p>

Solution Brainstorm

We should hook this and create spans. It only impacts elements annotated with the elementtiming attribute!

[AbhiPrasad]

#16589

duplicate of #13675