jni_register_sighandler off main thread

Registering native crash handler off main thread (to avoid ANR)

Test native crash handing

[ ] apply the patch from this Asana task to this PR
[ ] build and install and launch app
[ ] verify Native crash handler init pixel sent appears in logcat
[ ] verify Native crash handler successfully initialized. apperas in logcat
[ ] verify app crashes and Native crash pixel sent appears in logcat
[ ] In kibana, verify pixels appear when applying this filter pixel:m.app*.native.crash.*
[ ] pixels have the right params, main process name, right appVersion and right customTab true/false value

duckduckgo / Android