Also removed old, very unsafe node.osoutput(). We're now integrating cleanly
with the IDF/newlib way of redirecting stdout.
Added necessary depends in Kconfig to ensure VFS support is enabled, as
otherwise you'd only get a mysterious crash when attempting to enable
output redirection.
Changes have been kept to a minimum, but a serious chunk of work was
needed to move from 8266isms to IDFisms.
Some things got refactored into components/lua/common, in particular
the LFS location awareness.
As part of this work I also evicted our partition table manipulation
code, as with the current IDF it kept breaking checksums and rendering
things unbootable, which is the opposite of helpful (which was the
original intent behind it).
The uart module got relocated from base_nodemcu to the modules component
properly, after I worked out how to force its inclusion using Kconfig alone.