Sentry-dart: Implement Envelope based transport

[bruno-garcia]

In order to support attachments, and user feedback without the need of a native layer (web, windows, linux) we need a transport in Dart that supports envelopes.

[marandaneto]

there's no specs for rate-limiting yet but other SDKs already implemented it, eg Java https://github.com/getsentry/sentry-java/blob/main/sentry/src/main/java/io/sentry/transport/RateLimiter.java

[bruno-garcia]

There's also some info here: https://github.com/getsentry/develop/pull/171

[ueman]

It could be worth to look into Darts convert library for the serialization process.

[marandaneto]

It could be worth to look into Darts convert library for the serialization process.

we already use dart:convert for ser/deser, but this is a Sentry spec that contains JSON or binary data within a file, so not really related to it

[marandaneto]

iOS is a bit split up:
https://github.com/getsentry/sentry-cocoa/blob/master/Sources/Sentry/SentryDefaultRateLimits.m
https://github.com/getsentry/sentry-cocoa/blob/master/Sources/Sentry/SentryEnvelopeRateLimit.m
https://github.com/getsentry/sentry-cocoa/blob/master/Sources/Sentry/SentryConcurrentRateLimitsDictionary.m
https://github.com/getsentry/sentry-cocoa/blob/master/Sources/Sentry/SentryRateLimitCategoryMapper.m
https://github.com/getsentry/sentry-cocoa/blob/master/Sources/Sentry/SentryRateLimitParser.m

[denrase]

Thanks for all the links and help!