[WIP] Implement runtime-based IValidatableTypeInfoResolver implementation

[Copilot]

• Create the new RuntimeValidatableTypeInfoResolver class in src/Http/Http.Abstractions/src/Validation/RuntimeValidatableTypeInfoResolver.cs
  • Implement type validation with caching
  • Handle recursive type discovery with cycle detection
  • Create internal RuntimeValidatableTypeInfo and RuntimeValidatablePropertyInfo classes
  • Support property validation attributes
  • Support nullable reference types and required attributes
  • Handle enumerable types
• Update the validation service registration in ValidationServiceCollectionExtensions.cs
• Create unit tests for the new resolver in src/Http/Http.Extensions/test/
  • Test simple POCO classes with validation attributes
  • Test complex nested types with validation
  • Test collection types validation
  • Test handling of cyclic references
  • Test validation integration with real validator
• Run all tests to ensure existing functionality works

Fixes #61220.

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[captainsafia]

@copilot It looks like I hit a rate limit the last time I tried to request you. Can you start working on this again?

[captainsafia]

I was hoping that Copilot could handle this fairly "boring" task of mapping an implementation that used static analysis to an implementation that used dynamic analysis but it looks like the task is too large for the session limitations enforced by Copilot. :/