change(xtensa): Deprecate ".../xtensa_context.h" include path

This commit deprecates the "freertos/xtensa_context.h" and "xtensa/xtensa_context.h"
include paths. Users should use "xtensa_context.h" instead.

- Replace legacy include paths
- Removed some unnecessary includes of "xtensa_api.h"
- Add warning to compatibility header

tools/test_apps/system/panic/main/panic_utils/memprot_panic_utils_xtensa.c

@@ -4,7 +4,6 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#include "freertos/xtensa_context.h"
 #include "esp_private/panic_internal.h"
 
 #include "esp_rom_sys.h"