Migrate Elasticsearch role mapping resource and data source to Plugin Framework

[Copilot]

This PR migrates the elasticstack_elasticsearch_security_role_mapping resource and data source from the legacy Terraform SDKv2 to the modern Terraform Plugin Framework, bringing consistency with other recently migrated resources like system_user and enrich_policy.

Changes Made

New Plugin Framework Implementation

• Resource: Implemented in internal/elasticsearch/security/role_mapping/ following the established code organization pattern
• Data Source: Uses extracted read logic to maintain code reuse while eliminating mock resource instances
• Schema: Maintains full compatibility with existing configurations while adding proper validators and normalized JSON types
• JSON Handling: Uses jsontypes.NormalizedType{} for rules, role_templates, and metadata fields to suppress insignificant formatting differences

Key Features Preserved

• All existing attributes and their behavior remain unchanged
• Support for both roles and role_templates with exactly-one-of validation
• Custom elasticsearch_connection block support
• JSON encoding/decoding for complex fields with proper normalization
• Import functionality

Code Quality Improvements

• Extracted Read Logic: Created reusable readRoleMapping function returning RoleMappingData and framework diagnostics
• Framework Diagnostics: Updated all role mapping functions to use consistent framework diagnostics instead of mixed SDK/framework types
• Simplified Checks: Replaced verbose null/unknown checks with utils.IsKnown() helper
• Consistent Updates: Update operations now read back the modified resource for consistent results
• Removed Legacy Code: Deleted old SDKv2 resource files and unused imports
• Utility Functions: Replaced manual type conversion with utils.SetValueFrom and utils.SetTypeAs for cleaner code

Test Coverage

• Migrated all existing acceptance tests to the new structure
• Added SDK compatibility test using provider version 0.11.17 to ensure smooth migration for existing users
• Includes tests for create, update, role templates, and data source functionality

Migration Benefits

• Performance: Plugin Framework provides better performance and resource handling
• Type Safety: Stronger type validation and better error messages with normalized JSON types
• Future-Proof: Aligns with Terraform's long-term direction
• Consistency: Matches the pattern used by other migrated resources in this provider

The migration maintains 100% backward compatibility - existing Terraform configurations will continue to work without any changes required.

Recent Updates

• Migrated role mapping resource and data source to Plugin Framework
• Extracted read logic to reusable function
• Updated all functions to use framework diagnostics
• Added normalized JSON types for rules, role_templates, and metadata
• Removed old SDKv2 resource files
• Applied code formatting
• Simplified diagnostics handling in create and delete methods
• Added normalized JSON types to data source schema
• Replaced manual role type conversion with utility functions for cleaner code

Fixes #1279.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[cla-checker-service]

❌ Author of the following commits did not sign a Contributor Agreement:
d9f7381, e7af822, c4160f0, 3c6e7a1, 6a1e17a, 6727aac, 1667660

Please, read and sign the above mentioned agreement if you want to contribute to this project