esptool_py: add missing phony build targets for CMake

Adds targets erase_flash and monitor for users not using idf.py.
Closes https://github.com/espressif/esp-idf/issues/2420.

components/esptool_py/run_esptool.cmake

@@ -8,39 +8,14 @@
 #
 cmake_minimum_required(VERSION 3.5)
 
-if(NOT IDF_PATH OR NOT ESPTOOLPY OR NOT ESPTOOL_ARGS OR NOT ESPTOOL_WORKING_DIR)
-    message(FATAL_ERROR "IDF_PATH, ESPTOOLPY, ESPTOOL_ARGS, and ESPTOOL_WORKING_DIR must "
-        "be specified on the CMake command line. For direct esptool execution, it is "
-        "strongly recommended to run esptool.py directly.")
+set(TOOL "esptool.py")
+
+if(NOT ESPTOOLPY OR NOT ESPTOOL_ARGS)
+    message(FATAL_ERROR "ESPTOOLPY and ESPTOOL_ARGS must "
+        "be specified on the CMake command line. For direct execution, it is "
+        "strongly recommended to run ${TOOL} directly.")
 endif()
 
-# Note: we can't expand these environment variables in the main IDF CMake build,
-# because we want to expand them at flashing time not at CMake runtime (so they can change
-# without needing a CMake re-run)
-set(ESPPORT $ENV{ESPPORT})
-if(NOT ESPPORT)
-    message("Note: esptool.py will search for a serial port. To specify a port, set the ESPPORT environment variable.")
-else()
-    set(port_arg "-p ${ESPPORT}")
-endif()
-
-set(ESPBAUD $ENV{ESPBAUD})
-if(NOT ESPBAUD)
-    message("Note: Using default baud rate 460800. To modify, set ESPBAUD environment variable.")
-    set(ESPBAUD 460800)
-endif()
-
-include("${IDF_PATH}/tools/cmake/utilities.cmake")
-
-set(cmd "${ESPTOOLPY} ${port_arg} -b ${ESPBAUD} ${ESPTOOL_ARGS}")
-spaces2list(cmd)
-
-execute_process(COMMAND ${cmd}
-    WORKING_DIRECTORY "${ESPTOOL_WORKING_DIR}"
-    RESULT_VARIABLE result
-    )
-
-if(${result})
-    # No way to have CMake silently fail, unfortunately
-    message(FATAL_ERROR "esptool.py failed")
-endif()
+include("${CMAKE_CURRENT_LIST_DIR}/get_port_args.cmake")
+set(CMD "${ESPTOOLPY} ${port_arg} ${baud_arg} ${ESPTOOL_ARGS}")
+include("${CMAKE_CURRENT_LIST_DIR}/run_cmd.cmake")