WebGL exception during IL2CPP processing

[bitsandfoxes]

Reported on Discord

Triggering an exception causes the IL2CPP backend to throw one of its own.

We might need to disable the automatic integration of the IL2CPP exception processor for WebGL.

[tustanivsky]

Users can encounter this issue if the Enhanced stack trace mode not supported in IL2CPP builds was set via options. Even though the corresponding property is hidden for SentryUnityOptions one can still access it via the SentryOptions base class and accidentally modify its value. The solution that should prevent users from changing the default Unity's stack trace mode can be found in a linked PR.