jf docker scan: Provide an option to filter vulnerabilities by jfrog_research_severity

Is your feature request related to a problem? Please describe.
While performing the scan of any docker (containers) image using Jfrog Xray, we currently don't have the option to filter vulnerabilities by JFrog Research Severity score (extended_information.jfrog_research_severity in the report)

Describe the solution you'd like to see
Command line option to option to filter vulnerabilities by JFrog Research Severity score. In case of the JFrog Research Severity score being absent, the default severity should be used as a fallback

jf docker scan <IMAGE:TAG> --min-jfrog-research-severity="HIGH,CRITICAL"

Describe alternatives you've considered
Currently it may be possible to use a manual post-filtering of the output using tools like jq

Additional context
It would be useful to have the same option in the Watches/Policies functionality - to be able to setup some policy based on the JFrog Research Severity score (with the same fallback mechanism)

Start by tracing the jf docker scan vulnerability-filtering entry point and how extended_information.jfrog_research_severity and severity are read from reports. Then inspect the Watches/Policies functionality to understand whether the same filtering is shared. Done means the CLI option applies the requested severity thresholds, falls back when the research score is absent, and the policy behavior is defined or implemented.