Cooperative cancellation across ABP services/repositories/UOW via ICancellationTokenProvider. USE FOR: ICancellationTokenProvider.Token and Use; NullCancellationTokenProvider; HttpContextCancellationTokenProvider and RequestAborted; FallbackToProvider precedence; passing CancellationToken through methods. DO NOT USE FOR: background job retry (background-jobs-and-events); generic async performance (out of scope); HTTP auth (configure-openiddict-authentication).
