[FEATURE] Allow a user to exclude specific vulnerabilities from OSS Index

[DarthHater]

Much as we've done in the other tools, allow a user to exclude specific vulnerabilities so that they can be ignored from OSS Index.

Suggestions are to allow someone to have a .chelsea.json or .chelsea.yaml file in their repo, which would have a list of vulnerabilities they want ignored by chelsea.

This functionality could ignore off of:

• The OSS Index ID for the vuln
• The CVE title for the vuln
• The CWE title for the vuln

As well, as an extra mile type of step, you could allow someone to ignore the vuln for only a specific period of time. We did that on Nancy, so that people could exclude something if there was no way to upgrade that dependency, and then have it fail at a later date to remind them to check back in on it.

By default you'd check the repository for the file, but also allow someone to pass in a file via the command line from an alternative location.

If someone has ignored a vuln, it should not show up in the audit results, or specifically say it was ignored, and also not cause the application to exit with a non zero code (if it's the only vulnerability found).

Do not use the term whitelist related to this code.