Modified IFileMonitor and IArchive to use asynchronous methods.

I removed the IsReady property and IsReadyChanged events in favor of task-based asynchronous pattern.
Fixed occasional null pointer exception in MultithreadedAccessTests.
Modified test to sleep while waiting for currently executing tasks to complete.
Added a Thread.Sleep because the test fails on the Jenkins VM.
Fixed path to MSBuild Community Tasks in CreateServiceWithoutData.proj
Removed the obsolete ABB.SrcML.Data-Monolithic project
Renamed LiteralType.cs to LiteralKind.cs
Data csproj updated to include LiteralKind.cs
Fixed bug in testing whether an added directory is a child of an already-monitored one.
Updated class diagrams for SrcML Data
[#61829288] Implemented new abstract query class.
Changed AbstractFileMonitor to raise its update completed event on the main thread.
Moved the data repository out of the srcML service. It now has its own service.
Refactored AbstractArchive OnFileChanged event to simplify the setting of the "HasSrcML" flag.
Removed all status bar updating from SrcML Service.
Merge commit 'df91b4103862c7542d700ed884a1d0b8cc32be5f' into release