Change rate limiting logs to level warning or error

[philipphofmann]

Description

See getsentry/team-mobile#195.

[rwachtler]

Hey @philipphofmann ! I was wondering if the goal is just to update the log-level here to something like SENTRY_LOG_WARN(@"RateLimit is active for all envelope items.") (as the title of this issue states) or also have some additional log statement, which isn't bound to the condition that all items has to be rate-limited in order to print the log?

I've the first variant ready in a fork, let me know if I should open a PR.

SentryHttpTransportTests

[philipphofmann]

I think we should also log a warning here to communicate that one envelope item of the envelope was dropped.

sentry-cocoa/Sources/Sentry/SentryHttpTransport.m

Lines 229 to 237 in fc350a4

	/**
	* SentryEnvelopeRateLimitDelegate.
	*/
	- (void)envelopeItemDropped:(SentryEnvelopeItem *)envelopeItem
	withCategory:(SentryDataCategory)dataCategory;
	{
	[self recordLostEvent:dataCategory reason:kSentryDiscardReasonRateLimitBackoff];
	[self recordLostSpans:envelopeItem reason:kSentryDiscardReasonRateLimitBackoff];
	}

Yes, feel free to open a PR, @rwachtler. We will help you to merge it.