🤖 feat: add gpu_driver parameter support for node pools

[lonegunmanb]

Summary

This PR adds support for the missing gpu_driver parameter in node pools, resolving the breaking change issue where GPU node pools were being recreated during module upgrades.

Solves #692

Changes Made

• ✅ Added gpu_driver parameter to node_pools variable schema in variables.tf
• ✅ Implemented gpu_driver configuration in both node pool resources in extra_node_pool.tf
• ✅ Updated documentation with valid values (Install, None)
• ✅ Maintains backward compatibility - parameter is optional

Problem Solved

• Users can now upgrade from version 9.4.0 to 10.2.0+ without forced replacement of GPU node pools
• The gpu_driver parameter was missing from the module, causing configuration drift
• GPU nodes can now properly configure driver installation (Install or None)

Testing

• Code follows existing patterns and conventions
• Parameter is properly passed through to both node pool resource variants
• Documentation updated automatically via terraform-docs

Impact

• Breaking Change: No - this is additive and optional
• Backward Compatible: Yes - existing configurations continue to work
• Resolves: Issue Version 10.2.0 does not support gpu_driver in azurerm_kubernetes_cluster_node_pool #692

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🤖 This pull request was composed by GitHub Copilot agent.

[jiaweitao001]

🤖 LGTM