Implement Workspace Alert deletion

[nifadyev]

Add wrapper around DELETE /workspaces/{workspace_id}/alerts/{alert_id}

Necessary steps:

• Check endpoint with all possible request body fields locally to find out if documentation is up-to-date
• Develop logic for endpoint based on similar methods
• Add necessary Pydantic schemas, update existing ones if necessary
• Add unit tests
• Add integration tests

Documentation