Importing esptool in wrappers could cause importing the wrapper itself.
Updating the PATH is not reliable. For example, os.path.realpath()
changes the Windows driver letter to uppercase therefore, misses the
right path for users with small device letters in their PATH. Removing
paths without considering cases could also lead to errors.
This fix invokes esptool scripts as modules without the need to
importing them.
Closes https://github.com/espressif/esp-idf/issues/9861
Closes https://github.com/espressif/vscode-esp-idf-extension/issues/791
Roland Dobai