fix(esp-tls): address MR review comments for SE PSA driver

- esp_tls_mbedtls: require cert when PSA-backed server/client key is set
- esp_tls_mbedtls: drop redundant pk_init/x509_crt_init (calloc handles it)
- psa SE driver: copy callbacks/opaque_key by value (no lifetime coupling)
- psa SE driver: replace atomic CAS with simple null check on register
- psa SE driver: use sig_len from sign callback with bounds validation
- psa SE driver: validate pubkey_len returned by export_pubkey callback
- psa SE driver: check hash sub-alg in RSA PKCS1V15 branch of validate_request
- psa SE driver: align secure_element_register_callbacks doc with value-copy impl
- esp_https_server: initialize server_key in HTTPD_SSL_CONFIG_DEFAULT
- mbedtls: move SECURE_ELEMENT_DRIVER_ENABLED to esp_config.h for parity
  with ESP_ECDSA_DRIVER_ENABLED; drop target_compile_definitions
- docs: fix esp_tls_cfg_t -> esp_http_client_config_t cross-reference
- docs: check psa_import_key() status in ESP-TLS PSA example
- hints/error_output: point at CONFIG_MBEDTLS_SECURE_ELEMENT_DRIVER_ENABLED

(cherry picked from commit 08b567ef3b)

tools/test_idf_py/error_output.yml

@@ -50,7 +50,7 @@
     "HINT: The component 'component' could not be found. This could be because: component name was misspelled, the component was not added to the build, the component has been moved to the IDF component manager, the component has been removed and refactored into some other component or the component may not be supported by the selected target.\nPlease look out for component in 'https://components.espressif.com' and add using 'idf.py add-dependency' command.\nRefer to the migration guide for more details about moved components.\nRefer to the build-system guide for more details about how components are found and included in the build."
 
 'fatal error: tmp/atca_mbedtls_wrap.h: No such file or directory\n':
-    "HINT: To use CONFIG_ESP_TLS_USE_SECURE_ELEMENT option, please install `esp-cryptoauthlib` using 'idf.py add-dependency espressif/esp-cryptoauthlib'"
+    "HINT: To use the ATECC608A secure element, enable CONFIG_MBEDTLS_SECURE_ELEMENT_DRIVER_ENABLED and install `esp-cryptoauthlib` using 'idf.py add-dependency espressif/esp-cryptoauthlib'"
 
 'fatal error: brownout.h: No such file or directory\n':
     'HINT: The Brownout API (functions/types/macros prefixed with "esp_brownout") has been made into a private API. If users still require usage of the Brownout API (though this is not recommended), it can be included via  #include "esp_private/brownout.h".'