experiment with using propagation context (Part 3 of TwP)

[AbhiPrasad]

This is a draft PR that represents my experiments with implementing tracing without performance (aka using propagation context to generate sentry-trace if there is no span).

This is Part 3 on #8352

I've already identified some nice to have refactors we can make here, so I'm going to open up a new PR that does some fundamental changes to propagation context. Notably, I don't think we need to store spanId on propagation context nvm I thought wrong.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	21.79 KB (+0.05% 🔺)
@sentry/browser - ES5 CDN Bundle (minified)	68.5 KB (+0.09% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	20.09 KB (+0.03% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	59.75 KB (+0.07% 🔺)
@sentry/browser - Webpack (gzipped + minified)	21.7 KB (+0.04% 🔺)
@sentry/browser - Webpack (minified)	70.89 KB (+0.08% 🔺)
@sentry/react - Webpack (gzipped + minified)	21.72 KB (+0.04% 🔺)
@sentry/nextjs Client - Webpack (gzipped + minified)	50.13 KB (+0.08% 🔺)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	29.66 KB (+0.08% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	27.74 KB (+0.08% 🔺)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	49.44 KB (+0.02% 🔺)
@sentry/replay - Webpack (gzipped + minified)	43.12 KB (0%)
@sentry/browser + @sentry/tracing + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	69.09 KB (+0.03% 🔺)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	61.65 KB (+0.01% 🔺)