Move the bulk of the python code in the SPDX 3.0 classes into a library
file
(From OE-Core rev: aed6f8c1c2e291bde4d7172742790fa535b2fc7d)
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>