feat: add --cost-limit flag

[matheusfm]

Description

This PR adds the --cost-limit option with disabling support.

Linked Issues

Marvin fails when scanning a large ConfigMap.

How has this been tested?

1. Create a large ConfigMap:

   head -c 1048576 </dev/urandom | base64 | head -c 950000 > configmap-data.txt
   kubectl create configmap large-configmap --from-file=configmap-data.txt
   

2. Scan the current cluster:

   go run main.go scan
   

   Marvin will exit with a non-zero code and log the following errors:

   E0221 13:18:46.238360 2182897 scan.go:236] "msg"="failed to validate check M-201" "error"="evaluate error: operation cancelled: actual cost limit exceeded" "check"="M-201" "obj"="v1/ConfigMap/default/large-configmap"
   I0221 13:18:46.583668 2182897 scan.go:186] "msg"="scan finished with errors" 
   

3. Scan the cluster disabling the cost limit:

   go run main.go scan --cost-limit=0
   

   Marvin will finish successfully.

Checklist

• I have labeled this PR with the relevant Type labels
• I have documented my code (if applicable)
• My changes are covered by tests