ref(nextjs): [Experiment] Automatically wrap API route handlers

[lobsterkatie]

This PR uses webpack to wrap API request handlers in a try/catch, so that errors can be reported to Sentry. Currently, that wrapping must be done manually, using withSentry. This makes that process automatic.

The current implementation is pretty hacky - definitely open to suggestions of a better way. Regardless, here's how it works:

• We create a webpack loader, which then is added to the processors which run on API route files. It's passed a stringified version of the code from each file in question, and returns a stringified version of the code after it's been wrapped.
• In order to do the wrapping, we need the code as code, so we feed it to Node's internal compilation method.*
• We do the wrapping.
• In the stringified original code, we replace the original handler with our wrapped one. Literally. Like with string replacement. 🤦🏻‍♀️
• Since the wrapped function has a reference to the original function, we add the code of the original function back in, but as a function expression rather than an export.

*Unfortunately, in order to instantiate a Module object to use to do the compilation, we need the code we pass it to use commonJS-style imports, which there's no guarantee it does. So before we pass it to our loader, we run it through Babel, using a Babel plugin specifically designed for that exact transformation.

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	20.63 KB (+0.01% 🔺)
@sentry/browser - Webpack	21.5 KB (0%)
@sentry/react - Webpack	21.53 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	27.92 KB (+0.01% 🔺)

[HazAT]

We will ship the manual approach today #3462
this PR is still too unstable and doesn't work in all of our manual test cases.
We'll try to make it work tho in the coming days.

[ctrlaltdylan]

Woof heroic effort.

Makes me think this is a shortcoming with NextJS and not so much a Sentry problem.

If they had a dev friendly way of defining groups of API routes and wrapping handlers, then we wouldn't need this kind of workaround to inject wrappers.

[lobsterkatie]

This is out of date and whatever we decide to do here, we should start from the current version of the SDK, using this for reference if it turns out to be useful. Closing.