Attach memory info to watchdog terminations

[philipphofmann]

Description

The Sentry SDK could sample the memory information once every x seconds and store it with the app state on a bg thread and report that information when a watchdog termination occurs. Then, users would know if the watchdog termination was due to an OOM. This only works for OOMs that slowly add up and not for high spikes in memory pressure.

Related to #2514, #3890 and #3518.

[kahest]

It probably makes sense to tackle this as part of a larger initiative to improve OOM/Watchdog terminations - see linked issues above.