Redis 8 Compatibility and Support

[burythehammer]

Redis 8.0 Support

• Add validation to prevent explicit module configuration for Redis 8.0+ - Modules are bundled by default in Redis 8.0, so users cannot explicitly set them. The provider now returns a validation error if users attempt to configure modules
  for Redis 8.0 databases.
• Fix state drift for Redis 8.0 databases - The API returns all bundled modules for Redis 8.0 databases, but if modules weren't explicitly configured in Terraform, the provider no longer stores them in state. This prevents unnecessary
  destroy/recreate operations.
• Add support for query_performance_factor on Redis 8.0 - Updated validation logic to allow QPF on Redis 8.0+ databases since RediSearch is bundled by default.
• Fix subscription state handling after Redis version upgrades - Added wait for subscription to become active after upgrading Redis versions to prevent "SUBSCRIPTION_NOT_ACTIVE" errors during subsequent operations.

Test Improvements

• Refactor inline Terraform configs to external files - Moved all inline Terraform configuration constants to .tf files in provider/pro/testdata/ for better maintainability and consistency.
• Added Redis 8.0 tests:
  • TestAccResourceRedisCloudProDatabase_Redis8 - Tests provisioning a Redis 8.0 database
  • TestAccResourceRedisCloudProDatabase_Redis8_Upgrade - Tests upgrading from Redis 7.2 to 8.0
  • TestAccResourceRedisCloudProDatabase_Redis8_ModulesBlocked - Tests that modules cannot be explicitly set on Redis 8.0
• Optimize test execution time - Reduced resource sizes in test configs and simplified update steps to focus on key changes.

General improvements

• Refactored pro subscriptions to their own package for better organisation