[4.0] Category-based Ratelimiting

[HazAT]

SDKs that use the envelope endpoint should support Category-based Ratelimiting.

This is the code in JS
getsentry/sentry-javascript#2962

It's all about reading the x-sentry-rate-limits response header and keeping an internal map in the transport from type -> duration to know what has been rate limited.

[st0012]

@HazAT since this a new feature and not critical to the new release, I plan to add this in 4.1 (will be started right after 4.0 is released), sounds good?

[st0012]

Some additional information:

1. You can ignore the "smart_rate_limit" part, and also the "organization". All you have to deal with are the first two parts, namely: the delay, and the categories.
2. Match transactions to transaction and all other events to error.
3. If there is no category, for example like 48::organization:foobar, then this implicitly applies to ALL data. That is, sessions, transactions, and errors.
I recommend that you special case this in your mapping. Have a look at the python implementation:
- Follow the parsing logic here: https://github.com/getsentry/sentry-python/blob/c277ed5d1170a7d58fe3482173d391ae799fdc0a/sentry_sdk/transport.py#L153
- Enforcement is here: https://github.com/getsentry/sentry-python/blob/c277ed5d1170a7d58fe3482173d391ae799fdc0a/sentry_sdk/transport.py#L207