Populate Security-Severity Value

[gfs]

Is your feature request related to a problem? Please describe.
GitHub Code Scanning Recognizes a security-severity value to specify a CWE value for a finding. DevSkim doesn't have these values defined, but it might be nice to have that included in the rules. This would also require a small amount of work to then inject those values into the output sarif.

https://docs.github.com/en/code-security/code-scanning/integrating-with-code-scanning/sarif-support-for-code-scanning#reportingdescriptor-object

Follow up from #605, #606

Describe the solution you'd like
Each rule would need to be evaluated to determine the appropriate CWE level on a float scale from 0-10.