fix(feedback): Ensure feedback can be lazy loaded in CDN bundles

[mydea]

This was brought up in slack - if you use a CDN bundle (or the loader) without feedback included, and you try to lazy-load the feedbackIntegration, it fails as of today. The reason is that we check if window.Sentry.feedbackIntegration exists, which it does, because we register a shim integration for compatibility in the loader.

So this PR adds a property on the shim integration which we can check for during lazy loading. While at it, I also added a missing method to the feedback integration shim.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser	22.46 KB (0%)
@sentry/browser (incl. Tracing)	34.24 KB (0%)
@sentry/browser (incl. Tracing, Replay)	70.29 KB (0%)
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	63.63 KB (0%)
@sentry/browser (incl. Tracing, Replay with Canvas)	74.69 KB (0%)
@sentry/browser (incl. Tracing, Replay, Feedback)	87.3 KB (+0.02% 🔺)
@sentry/browser (incl. Tracing, Replay, Feedback, metrics)	89.15 KB (+0.02% 🔺)
@sentry/browser (incl. metrics)	26.76 KB (0%)
@sentry/browser (incl. Feedback)	39.4 KB (+0.03% 🔺)
@sentry/browser (incl. sendFeedback)	27.08 KB (0%)
@sentry/browser (incl. FeedbackAsync)	31.73 KB (+0.05% 🔺)
@sentry/react	25.22 KB (0%)
@sentry/react (incl. Tracing)	37.23 KB (0%)
@sentry/vue	26.6 KB (0%)
@sentry/vue (incl. Tracing)	36.08 KB (0%)
@sentry/svelte	22.59 KB (0%)
CDN Bundle	23.68 KB (+0.13% 🔺)
CDN Bundle (incl. Tracing)	35.92 KB (+0.08% 🔺)
CDN Bundle (incl. Tracing, Replay)	70.35 KB (+0.04% 🔺)
CDN Bundle (incl. Tracing, Replay, Feedback)	75.6 KB (+0.02% 🔺)
CDN Bundle - uncompressed	69.44 KB (+0.06% 🔺)
CDN Bundle (incl. Tracing) - uncompressed	106.36 KB (+0.04% 🔺)
CDN Bundle (incl. Tracing, Replay) - uncompressed	218.21 KB (+0.02% 🔺)
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	231.1 KB (+0.01% 🔺)
@sentry/nextjs (client)	37.08 KB (0%)
@sentry/sveltekit (client)	34.81 KB (0%)
@sentry/node	114.77 KB (-0.01% 🔽)
@sentry/node - without tracing	89.33 KB (-0.01% 🔽)
@sentry/aws-serverless	98.5 KB (-0.01% 🔽)