Update sumo builder utility

[Gamenot]

This is a step toward resolving #619. This updates the sumo source builder to generalize for other Ubuntu versions. This will be used to simplify building(and rebuilding) the debug version of SUMO.

The end intention is the following:

$ sumo_builder.sh -u 20.04 -s v1_16_0 --no-persist
# -s, --sumo-tag will cause a checkout (needed if using remote)
# -r, --repository will use a specific repository (default https://github.com/eclipse/sumo)
$ sumo_builder.sh -u 20.04 -r ~/repos/sumo --debug
Builder does not exist, generating a new container...
Build triggered.
...
Build output to "./build"
$ sumo_builder.sh -u 20.04 -r ~/repos/sumo --debug
Builder exists, reusing the container...
Rebuild triggered.
...
Build output to "./build"

TODO

• Target SUMO repository
• Add debug build option
• Option to persist builder container (default persist)
• Consider python version option

[Gamenot]

This exposed a funny bug in the CI where pytype test will run without any python files because the CI looks for .py which is in "README.pypi.md".

Not sure it is worth fixing.