[Bug] Action 'mergeCase' not mapped in v0 

### Request Type
Bug

### Problem Description
Merging an alert into a case action is not mapped on the case update operation in v0

### Steps to Reproduce
- Merge an alert into a case
- Consult liveflow json: the "operation" field is set to "Unknown" 

### Possible Solutions
Map the merge alert into case action to the operation case update