Calling sendAction with nil in a tight loop causes performance issue

[philipphofmann]

Description

A customer reported an issue in which a third-party library calls sendAction with nil target in a tight loop, for which the Cocoa SDK creates multiple breadcrumbs. As the SDK serializes breadcrumbs to SentryCrash, this adds a significant performance overhead.

An idea brought up by the customer is that the Cocoa SDK could ignore sendAction with nil target. Ideally, the SDK adds a backpressure mechanism for addBreadcrumb.