test(tracing): Add CLS tests.

[onurtemizkan]

Part of: #4262

Summary:

• Added a browser helper to simulate CLS scores in tests. (based on https://github.com/checkly/vitals-tester)
• Added @babel/preset-typescript to implement our browser helpers in Typescript.
• A test case for each CLS category, with assertions for cls.source.{n} tags.

[github-actions]

size-limit report

Path	Base Size (656017a)	Current Size	Change
@sentry/browser - CDN Bundle (gzipped)	19.59 KB	19.59 KB	+0.01% 🔺
@sentry/browser - CDN Bundle (minified)	62.5 KB	62.5 KB	+0.01% 🔺
@sentry/browser - Webpack	22.11 KB	22.11 KB	0%
@sentry/browser - Webpack - gzip = false	75.59 KB	75.59 KB	0%
@sentry/react - Webpack	22.14 KB	22.14 KB	0%
@sentry/nextjs Client - Webpack	46.33 KB	46.33 KB	0%
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	28.31 KB	28.31 KB	+0.01% 🔺

[AbhiPrasad]

Can we update the README with info on how the aliases work and how they should be used?

[onurtemizkan]

@AbhiPrasad, opened #4413 introducing @utils alias. I'll update this PR when we finalize that.