tools: installer: use bundled idf_tools when installing IDF 3.3.1, 4.0
tools: installer: use bundled idf_tools when installing IDF 3.3.1, 4.0

This is a workaround for the 'no-site-packages' bug in the version of
idf_tools.py shipped in v4.0 and v3.3.1 (see 7a18f02ac).

When installing IDF v4.0 and v3.3.1, the installer will use the
bundled version of idf_tools.py instead of the version which comes
with IDF.

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf