Move MWDT retention descriptors out of esp_hal_wdt and into esp_system
so the backup policy lives with the watchdog users, while keeping the
per-chip retention sources under the existing port/soc target
directories.
- Remove GPTIMER and TIMG related definitions from soc_caps_full.h files
- Move timer peripheral definitions to appropriate HAL layer files
- Update references across components to use proper HAL abstractions
- Consolidate timer group and GPTIMER capabilities organization
- Ensure consistent timer configuration across all ESP32 variants
This refactoring improves the separation of concerns between SOC
capabilities and HAL implementations for timer-related functionality.
