This adds ci.py a script that can be used to test changes to the base-images.
The script does the following:
1. Builds and pushes a test image for each base image. This will be used in step 3.
2. Finds which projects are buildable based on user specifications of: projects, build type (e.g. sanitizer/fuzzing engine) and which of these succeeded in production.
3. Submits builds for those projects.
4. Polls GCB to check which builds succeeded and which failed.
5. Returns 0 if all builds succeeded.
Currently this script is only useful to run locally.
Related: https://github.com/google/oss-fuzz/issues/7145
jonathanmetzman