Add performance measurement to Cart AJAX

[haeky]

PR Summary:

Start capturing RUM around cart interaction to express the buyers' experience when going through Dawn. These metrics will be extracted by perf-kit and emitted to our data pipeline.

What approach did you take?

Adding a Performance to be used in different cart operations.

• Performance.measureFromEvent: Measure against a starting event. This is useful when we need to measure the end of an asynchronous event.
• Performance.measure: Measure the time elapsed in a callback.

Testing steps/scenarios

Using the demo store, add an item to the store. Afterward, using the console, type performance.getEntriesByType("measure"); and you should see performance measurement. Here's the other different scenario to test:

• Changing the quantity
• Removing a line
• Changing a note

Demo links

• Store

Checklist

• Added PR summary for release notes
• Requested review from UX (Only for changes that are affecting the experience or perceivable visual details)
• Created a ticket for the help.shopify.com documentation team about updates to theme settings. (Internal-only task)
• Followed theme code principles
• Linted with Theme Check
• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility

[ludoboludo]

Looks good, just gotta revert the change for the settings_data.json

[tyleralsbury]

Tested cart functionality and it all seems good.

[tyleralsbury]

Suggested change

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