Improve AWS Lambda experience

[Lms24]

I investigated AWS lambda support in the last couple of days and found multiple issues we should tackle to improve the SDK/Usage experience with our @sentry/aws-serverless SDK and AWS Lambda layer:

### General AWS Lambda Support
- [ ] #12392
- [ ] #12407
- [ ] https://github.com/getsentry/sentry-javascript/pull/12430
- [ ] https://github.com/getsentry/sentry-docs/pull/10655

### ESM Lambda Support
- [ ] https://github.com/getsentry/sentry-javascript/pull/12833
- [x] Investigate why Otel Http Instrumentation doesn't record spans
- [ ] https://github.com/getsentry/sentry-docs/pull/10655

### ESM Lambda Layer
- [ ] https://github.com/getsentry/sentry-javascript/issues/12856

[G-Rath]

Not sure if you're already tracking this or what, but fwiw it looks like switching to @sentry/aws-serverless adds an extra 2.2mb to my lambdas - it doesn't sound like a stated or expected goal, and I imagine some "new" size is in new feature stuff, but it still feels like a weird jump given #11052 says "removes all GCP related code".

Something else I find telling is that installing @sentry/serverless only adds 19 packages whereas @sentry/aws-serverless adds 82 on my project apparently - again, not the end of the world and I've not done any digging, but thought you might be interested 🙂

The lambdas themselves are typescript based, compiled with serverless v3 + tsc as per https://github.com/ackama/serverless-aws-template

[Lms24]

@G-Rath the increase in dependencies and size is caused by us switching to OpenTelemetry for instrumentation. By default, the our AWS Serverless SDK does not include performance instrumentation (e.g. for databases like postgres). However, if you only use tsc to build your functions I'm fairly sure that some unused code and dependecies are not tree-shaken out. Meaning your build might be larger than it has to be.

Have you looked into bundlers like rollup? they should be able to tree-shake out all unused code.

That being said, I have never heard of sls before so not sure if it does any optimizations under the hood. My reference is basically manually zipping up a lambda function including its node_modules and deploying it with the AWS CLI. In this workflow, I know for sure that no code elimination is done at all.