feat(core): Update span performance API names

[AbhiPrasad]

As per the new changes in RFC 101 in getsentry/rfcs#113, update the span performance API names.

• startActiveSpan -> startSpan
• startSpan -> startInactiveSpan

https://github.com/getsentry/rfcs/blob/main/text/0101-revamping-the-sdk-performance-api.md

startActiveSpan is deprecated, while startInactiveSpan is being introduced. The breaking change is that startSpan is being changed, but considering that basically no-one is using the startSpan API, we should be fine to break here for correctness reasons. Better break now than to have everyone refactor their code in v8.

This is a breaking change, so maybe we decide against doing the rename in JavaScript - thoughts? #8970 also brought up that I forgot to export the span creator methods in browser SDKs, so perhaps we can get away with the change.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	75.36 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)	70.09 KB (+0.29% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	28.42 KB (+0.75% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	20.48 KB (+1.38% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	221.53 KB (+0.32% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	85.82 KB (+0.82% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	60.66 KB (+1.5% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	31.3 KB (+0.62% 🔺)
@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)	93.26 KB (+0.01% 🔺)
@sentry/nextjs Client - Webpack (gzipped)	50.83 KB (-0.01% 🔽)

[ssanderson]

#8970 also brought up that I forgot to export the span creator methods in browser SDKs, so perhaps we can get away with the change.

re: this, FYI, these APIs are exposed from @sentry/core at the moment, which is the workaround I started using after figuring out what was going on in the linked issue. If there are others doing similar workarounds, then the rename might cause some real breakage, since a user who was using only startSpan will have their code start silently behaving differently after upgrading.

It's easy enough for me to update my changes since I've only just started trying to use this (and also I'm only using startActiveSpan anyway, so I'll at least get a compilation error from typescript), but pure JS users, or typescript users who are using startSpan might see this as a larger brekage.

[Lms24]

Changes LGTM. As for merging this:

Let's chat about it in Daily. I think it'd be reasonable to break, especially since the original APIs were out for a little over a week. If we decide to hold off, then let's still do this in v8 because I think ultimately, we want to align with the amended RFC/what we discussed yesterday.

[AbhiPrasad]

I thought about this more, considering the current names map exactly to OTEL let's just keep them around until we properly break in v8.

Better not risk it since it was added to docs.

[AbhiPrasad]

After chatting in our daily we decided that we're going to change the behavior for just startSpan. Although it's a breaking change, most people are using startActiveSpan anyway.

We'll deprecate the startActiveSpan export and replace it with startSpan.