Fix | Change s_enclaveProviders to ConcurrentDictionary

[johnnypham]

Fixes #1444

[DavoudEshtehari]

Could you include a test?

[johnnypham]

Could you include a test?

Any suggestions on how to consistently force concurrent access to s_enclaveProviders?

[DavoudEshtehari]

My suggestion here is to provide the race condition by sending parallel requests to s_enclaveProviders blended with delay and async call.

[johnnypham]

My suggestion here is to provide the race condition by sending parallel requests to s_enclaveProviders blended with delay and async call.

Again, that doesn't consistently force concurrent access. I think the use case for a test should be reproducible on every run. I don't mind adding it but it wouldn't add any value imo. Essentially the test would just be verifying whether a ConcurrentDictionary is actually thread-safe.

[DavoudEshtehari]

In this case it could be a candidate for stress testing.
Just to be more precise, the extension methods' thread safety hasn't been guaranteed.