### What?
Adding a `performance.mark` for next/third-parties for feature measurement
### Why?
We’re working with the Chrome Speed Metrics team to develop an API to better identify specific features used by frameworks and/or CMS platforms. Instead of a entirely new API surface, we've agreed to use `performance.mark` as the signal along with mark_use_counter as a signature.
In the past, we've used HTML attributes for Next which have been helpful, but this will improve the accuracy of our feature detection. In this instance, this will better help us analyze and compare sites that use `@next/third-parties` versus those that don't, and to see if our efforts are actually improving performance.
It's worth noting that this metric will have a public arm, but we're starting to incorporate its usage now to gather early data. performance.mark calls are indeed low-overhead and shouldn't affect loading/rendering performance whatsoever.
Hi,
I added a key in the map iteration of scripts in Youtube Embed. I use the index as a key but maybe there are a better solution about this like script.url + index 🤔
There isn't open related issues with this PR as this moment.
```js
{scripts?.map((script, index) => (
<Script
key={index}
src={script.url}
strategy={scriptStrategy[script.strategy] as ScriptProps['strategy']}
stylesheets={stylesheets}
/>
))}
```
