Update MessagePack NuGet files and improve type handling - #597

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, microsoft/setup-msbuild@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Possible null reference argument for parameter 'entity' in 'void AddAttachInferrer.Visit(Entity entity)'.

Possible null reference argument for parameter 'propertyName' in 'void ValidationResultCollection.ReplaceErrors(string propertyName, IEnumerable<ValidationResult> newResults)'.

Dereference of a possibly null reference.

Change return type of method 'CreateProjectionProperties' from 'System.Collections.Generic.ICollection<System.ComponentModel.PropertyDescriptor>' to 'System.Collections.Generic.List<System.ComponentModel.PropertyDescriptor>' for improved performance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859)

Change return type of method 'GetMethodParameters' from 'System.Collections.Generic.IEnumerable<OpenRiaServices.Server.DomainOperationParameter>' to 'System.Collections.Generic.List<OpenRiaServices.Server.DomainOperationParameter>' for improved performance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859)

Possible null reference return.

Field 'WebContextBase._started' is never assigned to, and will always have its default value false

Possible null reference argument for parameter 'entity' in 'void AddAttachInferrer.Visit(Entity entity)'.

Dereference of a possibly null reference.