feat(core): Introduce startSpanManual

[AbhiPrasad]

Based on #8911 and convos in slack, it was brought up that we might need to expose a method that works similar to startSpan, but that does not automatically finish the span at the end of the callback.

This is necessary when you have event emitters (res.once) or similar.

Sentry.startActiveSpanManual(ctx, (span, finish) => {
  // do something with span
  // when you're done, call finish()
  finish();
});

[mydea]

What about having an API like this:

Sentry.startActiveSpanManual(ctx, function(span, finish) {
  // do something with span
  // when you're done, call finish()
  finish();
}

Would make overwriting this for OTEL easier, as we can under the hood change what finish does?

[AbhiPrasad]

What about having an API like this

I like that a lot, thanks for the suggestion!

[AbhiPrasad]

temporarily putting this off until we make decision about naming tomorrow.

[AbhiPrasad]

updated based on changes in #8971

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	75.37 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	31.27 KB (0%)
@sentry/browser - Webpack (gzipped)	21.87 KB (0%)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	70.18 KB (+0.13% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	28.49 KB (+0.26% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	20.56 KB (+0.4% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	221.88 KB (+0.16% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	86.17 KB (+0.41% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	61.01 KB (+0.58% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	31.35 KB (+0.2% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	75.39 KB (+0.01% 🔺)
@sentry/react - Webpack (gzipped)	21.9 KB (0%)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	93.25 KB (-0.01% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	50.83 KB (+0.01% 🔺)