Add ESP certificate bundle feature

Adds the ESP certificate bundle feature that enables users to bundle a
root certificate bundle together with their application.

Default bundle includes all Mozilla root certificates

Closes IDF-296

docs/zh_CN/api-reference/protocols/esp_crt_bundle.rst

@@ -0,0 +1 @@
+.. include:: ../../../en/api-reference/protocols/esp_crt_bundle.rst

docs/zh_CN/api-reference/protocols/index.rst

@@ -17,6 +17,7 @@
     Modbus slave <modbus>
     Local Control <esp_local_ctrl>
     :esp32: ESP Serial Slave Link <esp_serial_slave_link>
+    Certificate Bundle <esp_crt_bundle>
 
 此 API 部分的示例代码在 ESP-IDF 示例工程的 :example:`protocols` 目录下提供。