Add provider validation and error handling

[wbreza]

Summary: Implement comprehensive validation and error handling for multi-provider scenarios, ensuring clear diagnostics and recovery options.

Acceptance Criteria:

• Provider availability and version validation
• Pre-deployment validation for each provider
• Standardized error reporting across providers
• Provider-specific error translation and guidance
• Rollback and recovery procedures for mixed-provider failures
• Diagnostic logging and troubleshooting support

[spboyer]

Covered by the YAML-driven error handling pipeline (#6827) and related PRs. Provider validation errors are now handled with actionable guidance:

• NoRegisteredProviderFound: suggests az provider register command (Add RBAC and authorization error rules for deployment failures #6846)
• InvalidTemplate/ValidationError: template validation guidance (Ability to easily provide custom error messages/suggestions/docs for errors. #6827)
• LocationNotAvailableForResourceType: dynamic region suggestions via ARM API (Ability to easily provide custom error messages/suggestions/docs for errors. #6827)
• AuthorizationFailed/Forbidden/RequestDisallowedByPolicy: RBAC and policy guidance (Add RBAC and authorization error rules for deployment failures #6846)
• Merged: error classification (Improve error classification for unknown and network errors #6803), soft-delete detection (Add soft-delete conflict detection hints for deployment errors #6810)