feat(core): add sample rate for Vercel analytics and speed insights

[chanceaclark]

What/Why?

Adds an opinionated default on the sample rates for both Vercel Speed Insights and Vercel Analytics. Most of the time you don't need to capture 100%, especially on a heavily trafficked site.

For Vercel Analytics, there was a little lifting that was needed to be done. We don't necessarily want to send events 25% of the time, but rather 25% of the users get analytics tracked per session.

Testing

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 3ac314d1cdfc1dbe983773571a980971fed2dee3

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@bigcommerce/catalyst-core	Minor

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[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated (UTC)
catalyst-latest	✅ Ready (Inspect)	Visit Preview		May 7, 2024 3:35pm
catalyst-test-store	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	May 7, 2024 3:35pm

3 Ignored Deployments

Name	Status	Preview	Comments	Updated (UTC)
catalyst-1millionproducts-store	⬜️ Ignored (Inspect)	Visit Preview		May 7, 2024 3:35pm
catalyst-au	⬜️ Ignored (Inspect)	Visit Preview		May 7, 2024 3:35pm
catalyst-uk	⬜️ Ignored (Inspect)	Visit Preview		May 7, 2024 3:35pm

[github-actions[bot]]

⚡️🏠 Lighthouse report

Lighthouse ran against https://catalyst-latest-g11gqhptt-bigcommerce-platform.vercel.app

🖥️ Desktop

We ran Lighthouse against the changes on a desktop and produced this report. Here's the summary:

Category	Score
🟢 Performance	99
🟢 Accessibility	100
🟢 Best practices	100
🟢 SEO	90

📱 Mobile

We ran Lighthouse against the changes on a mobile and produced this report. Here's the summary:

Category	Score
🟠 Performance	89
🟢 Accessibility	100
🟢 Best practices	100
🟢 SEO	92