tools/ci.sh: Add helper script to run CI tasks.
tools/ci.sh: Add helper script to run CI tasks.

The aim is for this script to be used on any CI platform, as well as run
locally.

Signed-off-by: Damien George <99e6b749acbfbe2a596df99e91d24d6e1fdbee00@micropython.org>

pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython,pfalcon/micropython