feat(core): Add span.end() to replace span.finish()

[mydea]

To align with OTEL spans.

This also deprecates span.finish(), and also makes sure that end() accepts both ms as well as s timestmaps (to align this with OTEL in the future, which accepts ms only).

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	75.63 KB (+0.05% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	67.06 KB (+0.06% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	60.65 KB (+0.09% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	31.64 KB (+0.09% 🔺)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	30.22 KB (-0.01% 🔽)
@sentry/browser - Webpack (gzipped)	21.91 KB (0%)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	73.07 KB (+0.06% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	64.77 KB (+0.07% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	30.98 KB (+0.14% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	22.95 KB (-0.02% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	203.16 KB (+0.03% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	93.08 KB (+0.07% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	68.07 KB (-0.01% 🔽)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	33.97 KB (+0.27% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	67.44 KB (+0.06% 🔺)
@sentry/react - Webpack (gzipped)	21.95 KB (0%)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	84.21 KB (+0.06% 🔺)
@sentry/nextjs Client - Webpack (gzipped)	48.83 KB (+0.08% 🔺)
@sentry-internal/feedback - Webpack (gzipped)	16.56 KB (0%)