Enable Snyk and White-source scanning on knative repos

Problem
We see some dependencies that are considered as vulnerable by both Snyk and White-source scanning. I found out about this because our organization does the scanning after we clone the repo. Keda does both snyk and white-source scanning so I would like to propose that we enabled these 2 scans on this repo as well so that any vulnerable libraries could be caught on PR and people no longer open git issues on vulnerable libraries and users that have dependency on this repo do not have to patch the vulnerable libraries themselves. Any new vulnerable libraries introduced by contributors should be caught immediately after PR creation and commits. Existing libraries that are considered to have vulnerabilities should be caught by nightly scan.

Start by examining how Keda performs Snyk and White-source scanning, then inspect this repository's existing pull-request, commit, and nightly scan configuration. Done means newly introduced vulnerable dependencies are checked on pull requests and commits, while existing vulnerabilities are detected by the nightly scan.

Written by the indexing model from the issue text.