west: esp32: use Python interpreter to execute ESP tool

The ESP tool is being executed directly in the esp32 runner,
assuming the tool is executable by itself. However, it would
fail under Windows as subprocess.check_call() cannot execute
Python scripts directly. The fix is to execute the Python
interpreter and passing the script path as a command line
parameter.

Fixes #19098

Signed-off-by: Daniel Leung <daniel.leung@intel.com>