Implement proper configuration validation for ADO.NET extensions

[coderabbitai]

Description

Replace manual connection string validation in ADO.NET Orleans extensions with proper .NET configuration validation patterns.

Background

Currently, the ADO.NET extensions methods manually validate connection strings using basic null checks. .NET provides built-in configuration validation mechanisms through Microsoft.Extensions.Options that would be more robust and performant.

Proposed Solution

Implement validation using:

• ValidateDataAnnotations() for declarative validation
• ValidateOnStart() for early validation during application startup
• Custom validation methods for connection string specific checks
• Integration with the existing ArgumentNullException.ThrowIfNull pattern where appropriate

Benefits

• Better integration with .NET's configuration system
• Improved error messages and validation feedback
• Consistent validation patterns across the codebase
• Performance optimizations from built-in validators

Files to Update

• src/Hosting/HostApplicationBuilderExtensions.AdoNet.cs
• Add configuration option classes with validation attributes
• Update extension methods to use validated configuration options

References

• PR: Add ADO.NET Orleans extensions for clustering, persistence, and reminders #11
• Discussion: Add ADO.NET Orleans extensions for clustering, persistence, and reminders #11 (comment)

Requested by: @snovak7