1. Add `centipede` to `DEFAULT_ENGINES`.
2. Remove the `fuzzing_engines` attribute from `project.yaml`s if
redundant (i.e., all default engines are included in that YAML file).
3. Temporarily disable `centipede` on `c`/`c++` projects that previously
use all `DEFAULT_ENGINES` (200 projects did not specify
`fuzzing_engines` in `project.yaml`) so that we can gradually enable
centipede later them later.
* [presubmit] Enforce language attribute in projectt.yaml to be always set.
* Update documentation, better presubmit check, new project template.
* add docstring to templates.py
* Add example values in the project.yaml template and remove python value for now
* Add "project: c++" to 256 projects
* format
* Add labels and selective_unpack sections to the presubmit check
* fix incorrect auto_ccs format in three projects
* fix nss emails after rebase
Dongge Liu