The Key Manager hardware peripheral in its current form needs further
design changes before it can be offered as a production feature.
Until a revised peripheral design is available, withdraw ESP-IDF
support for it on all Key Manager capable targets.
On ESP32-P4 rev < 3.0, Key Manager is software-disabled, but the public
esp_key_mgr.h APIs had no runtime check.
Calls using HMAC/DS/PSRAM key types fell through to
HAL_ASSERT("Unsupported ...") paths in key_mgr_ll.h. Gate
each public API with key_mgr_ll_is_supported() and return
ESP_ERR_NOT_SUPPORTED cleanly instead.