fix(utils): Don't attach context lines to stack frames without line number

[lforst]

This PR fixes a bug that breaks grouping in Sentry. Currently, when a stack frame doesn't have a line number we attach context lines based on line number 0. This is simply wrong and conflicts with grouping algorithms. We solve this by not attaching context lines at all for frames that do not have line numbers.

Some (ephemeral) context: https://sentry.slack.com/archives/GUCRT2B70/p1671103033977659

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	19.78 KB (-0.01% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	61.27 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.57 KB (+0.02% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	54.8 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	20.34 KB (0%)
@sentry/browser - Webpack (minified)	66.48 KB (0%)
@sentry/react - Webpack (gzipped + minified)	20.36 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	47.57 KB (0%)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	26.76 KB (+0.01% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	25.19 KB (0%)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	41.89 KB (+0.03% 🔺)
@sentry/replay - Webpack (gzipped + minified)	38.12 KB (+0.02% 🔺)