[SR] Add session replay envelope and events

[romtsn]

#skip-changelog

📜 Description

You can read up more about the new envelope spec here getsentry/rfcs#129

It has a good chunk of work that you've done during the hackweek, but with several enhancements:

• RRWeb events are now typed
• Properly capture replay events with recordings in SentryClient and record client reports if e.g. an event is dropped by an event processor
• Also have a separate method for applying scope as replay events don't have everything as regular events (e.g. no breadcrumbs)
• I had to introduce a new MapObjectReader and extract an ObjectReader interface from JsonObjectReader but I made a separate PR for this (this one will be failing until the other one is merged)

💡 Motivation and Context

Closes #3213

💚 How did you test it?

With tests

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

Glue recording and envelopes together

[romtsn]

@markushi @stefanosiano I'll wait with merging #3215 otherwise it'll be hell to review this

[markushi]

Left a few minor comments, and stopped at some point adding final and @NotNull annotations. But apart from that, LGTM!

[romtsn]

and stopped at some point adding final and @NotNull annotations

thank you! I will revise that myself and add where necessary

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	374.76 ms	457.26 ms	82.50 ms
Size	1.70 MiB	2.28 MiB	591.02 KiB

Previous results on branch: rz/feat/session-replay-envelopes

Startup times

Revision	Plain	With Sentry	Diff
6650dc9	424.67 ms	506.40 ms	81.73 ms
8aeeb6b	364.00 ms	434.31 ms	70.31 ms

App size

Revision	Plain	With Sentry	Diff
6650dc9	1.70 MiB	2.28 MiB	591.02 KiB
8aeeb6b	1.70 MiB	2.28 MiB	591.02 KiB

[brustolin]

I reviewed only the Session Replay related changes (all the serialization change could have been a different PR), and it looks good.
I wrote just a few comments for discussion.