Automated indexer project tracking based on OSV.dev advisories

[another-rex]

Is your feature request related to a problem? Please describe.
Indexer misses repositories publishing new C/C++ advisories that previously didn't exist in OSV.dev.
Describe the solution you'd like
By using OSV.dev advisories as a source of github repositories to index, we can always be up to date with indexer converage.

Describe alternatives you've considered
Keep the config bucket updated with a regular cron that checks new repositories. This doesn't provide much benefit over directly using the information contained in OSV.dev.

[another-rex]

The current config includes:

type RepoConfig struct {
	Address          string   `yaml:"address"`
	Name             string   `yaml:"name"`
	Type             string   `yaml:"type"`
	BaseCPE          string   `yaml:"base_cpe"`
	BranchVersioning bool     `yaml:"branch_versioning,omitempty"`
	HashAllCommits   bool     `yaml:"hash_all_commits,omitempty"`
	FileExts         []string `yaml:"file_extensions"`
}

each entry needs to either be derived from the existing Bug entry, or be added/stored in the bug entry.

Mapping will look like

Address => repo_url
Name    => project
Type      => Git (hard coded)
BaseCPE   => Not used?
BranchVersioning  => ?? (need to be a new field)
HashAllCommits    => ?? (might need to be a new field)
FileExts                    => (hardcoded)

[github-actions]

This issue has not had any activity for 60 days and will be automatically closed in two weeks

[github-actions]

This issue has not had any activity for 60 days and will be automatically closed in two weeks

See https://github.com/google/osv.dev/blob/master/CONTRIBUTING.md for how to contribute a PR if you're interested in helping out.