Adding .ConfigureAwait(false) to async library code

[BitWizJason]

Missing .ConfigureAwait(false) on async method calls was causing deadlocks in our application. Added modifier to all async methods in QueryBuilder and SqlKata.Execution libraries. Also added ConfigureAwaitChecker.Analyzer nuget package to help enforce continued use of .ConfigureAwait(false) through warnings in the code if it is missing. Nuget package added to both projects.