Use bools and enums with Interlocked.CompareExchange

[jamescrosswell]

In various places in the solution we're using int instead of bool so that we can make use of the Interlocked class, which historically did not support bool and enum. For example: https://github.com/getsentry/sentry-dotnet/blob/96a116c6076d358d6e0c06a1f012c1ed2c7a65d1/src/Sentry.Profiling/SampleProfilerSession.cs#L58-L68

With .net9 Interlocked.CompareExchange supports more types.

We should leverage the new type support to tidy up our code.