Refactor Extensions class and update project dependencies

- Comment out `protobuf-net` package reference in `Core.csproj` for potential future use.
- Add new `using` directives in `Extensions.cs` and remove `ProtoBuf` namespace, indicating a shift away from Protobuf serialization.
- Reintroduce and restructure previously removed methods in the `Extensions` class, with some methods commented out for reference.
- Update `GetPropertyValue` method to use `ArgumentNullException.ThrowIfNull` for .NET 6.0 compatibility while maintaining support for earlier versions.
- Comment out several serialization and XML handling methods, suggesting a potential deprecation or design shift.
- Overall, these changes enhance code clarity and maintain compatibility with newer frameworks.

Enhance documentation and null-checking in data classes

Added XML documentation comments to `DataReaderExtensions.cs` and `DynamicDataRecord.cs`. Improved null-checking using `ArgumentNullException.ThrowIfNull` for .NET 6.0 and greater. Updated method implementations for better readability and maintainability while preserving functionality.

Update versioning to 7.4 in Release configuration

The version number in the `Version` property of the
`PropertyGroup` for the Release configuration has been
changed from `6.1.$(Build).$(Revision)` to
`7.4.$(Build).$(Revision)`, reflecting a new major version
update from 6.x to 7.x.

Update release.yml

Update package versions in Directory.Packages.props

Updated several packages from version 8.x.x to 9.0.2, including
Microsoft.EntityFrameworkCore and Microsoft.Extensions.*.
Removed an extra line before the closing <Project> tag.