Improve debouncer to throttle only on high volume

[bruno-garcia]

trafficstars

Currently when two log entries are captured sequentially within a second, the second is not tracked as crumb or event. This is suboptimal (as raised by users https://github.com/getsentry/sentry-unity/issues/294).

The debouncer should only drop items once it detects things are spammy. Not by default.

1. Turn off the debouncer by default. Add a Checkbox to turn it back on.
2. Add a deduplication strategy in the .NET SDK that takes into account high volume of duplicate messages so we can use it in the Unity SDK