[PLAT-5412] Cocoa mixed-type stacktraces

[nickdowell]

Goal

A change in the design of how React Native native promise rejections would be represented, from an event with multiple errors to a single event with stack frames of mixed types.

This depends on bugsnag/bugsnag-cocoa#902

Changeset

• Updated bugsnag-cocoa
• Changed nativeStack parsing to append native stack trace to top of stacktrace

Testing

• Manually verified using React Native example app

[bugsnagbot]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	40.70 kB	12.54 kB
After	40.70 kB	12.54 kB
±	No change	No change

Generated by 🚫 dangerJS against 24bfb8e

[github-actions]

@bugsnag/browser bundle size diff

	Minified	Minfied + Gzipped
Before	40.70 kB	12.54 kB
After	40.70 kB	12.54 kB
±	No change	No change

Generated by 🚫 dangerJS against 91bc1c9

[bengourley]

New bugsnag-stacktrace-types header present and exception/stackframe type values all as expected for RN promise rejections.