feat(core): Allow to pass forceTransaction to startSpan() APIs

[mydea]

This will ensure a span is sent as a transaction to Sentry.

This only implements this option for the core implementation, not yet for OTEL - that is a follow up here: #10807

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	77.39 KB (+0.16% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	68.64 KB (+0.15% 🔺)
@sentry/browser (incl. Tracing, Replay with Canvas) - Webpack (gzipped)	72.55 KB (+0.14% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	62.15 KB (+0.16% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	32.82 KB (+0.32% 🔺)
@sentry/browser (incl. browserTracingIntegration) - Webpack (gzipped)	32.82 KB (+0.32% 🔺)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	30.91 KB (0%)
@sentry/browser (incl. sendFeedback) - Webpack (gzipped)	30.91 KB (0%)
@sentry/browser - Webpack (gzipped)	22.19 KB (0%)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	75.79 KB (+0.06% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	67.54 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	33.33 KB (+0.14% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	24.74 KB (+0.06% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	211.44 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	100.16 KB (+0.17% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	73.96 KB (+0.25% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	36.39 KB (+0.11% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	68.93 KB (+0.16% 🔺)
@sentry/react - Webpack (gzipped)	22.22 KB (0%)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	85.35 KB (+0.12% 🔺)
@sentry/nextjs Client - Webpack (gzipped)	49.76 KB (+0.2% 🔺)
@sentry-internal/feedback - Webpack (gzipped)	17.14 KB (0%)

[mydea]

maybe forceTransaction would be a better option name than isTransaction, because this is rather what it doe?

[lforst]

This makes sense to me. I'd love to revisit the name for this if we have a plan what it's gonna look like in the product but that is a future-us issue!