revert change to structs from classes for IntOrString and ResourceQuantity, and handle null values in YAML converters

[tg123]

this fix #1672

[Copilot]

Pull Request Overview

This PR reverts IntOrString and ResourceQuantity from struct to class types and adds null safety handling in their YAML converters. The changes address issue #1672 which likely involved null reference exceptions when using these types.

• Converts IntOrString and ResourceQuantity from structs back to classes
• Adds null-safe handling in YAML converters with conditional operators
• Includes a comprehensive E2E test for V2 Horizontal Pod Autoscaler functionality

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/KubernetesClient/Models/IntOrString.cs	Reverted from struct to class and added null safety in implicit string conversion
src/KubernetesClient/Models/ResourceQuantity.cs	Reverted from struct to class
src/KubernetesClient/Models/IntOrStringYamlConverter.cs	Added null-conditional operator for safe YAML serialization
src/KubernetesClient/Models/ResourceQuantityYamlConverter.cs	Added null-conditional operator for safe YAML serialization
tests/E2E.Tests/MinikubeTests.cs	Added comprehensive E2E test for V2HorizontalPodAutoscaler operations

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[brendandburns]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: brendandburns, tg123

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