Expose on_rate_limit as part of the transport contract

[sl0thentr0py]

I see, thanks for the explanation of your use case.
So a few points

• we never do a retry ever on our side, a dropped event is a dropped event
• the server's rate limiting is merely interpreted as 'stop doing stuff for a while'
• technically it is breaking yes, but this is considered internal to the http transport implementation and not really part of the API contract

That said, there are a couple of options for you now

• make your own transport deriving from Sentry::HTTPTransport and override send_data there and do what you wish there
• I can expose a on_rate_limit hook in the transport class similar to on_error to make that easier so you just need to define that one method to retry

does that work?

Originally posted by @sl0thentr0py in #2216 (comment)