Updated `DigitalData.UserManager.Domain.csproj` to support .NET 4.6.2, 7.0, 8.0, and 9.0. Adjusted implicit usings and nullable reference types settings based on the target framework, disabling nullable types for `net462` and enabling them for others.
Refactored entity classes (`BaseEntity`, `ClientUser`, `Group`, `GroupOfUser`, `Module`, `ModuleOfUser`, `User`, and `UserRep`) to conditionally include nullable reference types. Added `?` operator for string properties in .NET 7.0 and above, enhancing code safety and reducing null reference exceptions.
Updated `DigitalData.UserManager.Domain.csproj` to target .NET Framework 4.6.2 alongside .NET 7.0, 8.0, and 9.0. Corrected `PackageTags` from "user maanger" to "user manager" and added property groups for implicit usings and language versions.
Introduced nullable reference types in entity classes (`BaseEntity`, `ClientUser`, `Group`, `User`, etc.) for enhanced type safety. Updated properties in the `User` and `UserRep` classes to use the new nullable syntax, ensuring consistency across the codebase.
These changes improve compatibility with newer C# features and maintain support for multiple frameworks.
