[Tidyup] Mongo no longer needed in main RDMP repo #2037
Description
The Mongo Nuget package was added to RDMP as a workaround for RdmpDicom needing it and native libraries (like libmongocrypt.dll) in plugin files causing issues; Mongo is now native-free/all-managed, so this dependency can be moved back to RdmpDicom itself where it belongs.