Allow defining a list of namespace to be scanned

[jvanz]

Currently the audit scanner allows users to define a single namespace to be scanned using the CLI flag --namespace.

audit-scanner/cmd/root.go

Line 138 in 0a92ddc

rootCmd.Flags().StringP("namespace", "n", "", "namespace to be evaluated")

We should update this flag to allow a list of namespaces to be scanned. Therefore, it is easier if users want to run multiple audit scanner jobs each one scanning different set of namespaces.