esp_openthread_rcp_version_set() function

- ESP_OK on success - ESP_FAIL if fail to set RCP version string

This function should be called before esp_openthread_init. When the RCP version string is not an empty string, compatibility checks will be performed during the initialization of the ESP OpenThread radio spinel. The `esp_openthread_compatibility_error_callback` will be triggered if the desired RCP version does not match the actual version running on the RCP. If needed, a NULL parameter can be passed to clear the version string.