audit logs for entitlements

**Is your feature request related to a problem? Please describe.**
event logs are incomplete when a Group/User is removed from an entitlement.

**Describe the solution you'd like**
When a Group/User is removed from an entitlement the log must contain information about what entitlement the
Group/User is removed from.

**Describe alternatives you've considered**

**Additional context**
When we add a Group we get:
` "model": {
"app": "authentik_policies",
"model_name": "policybinding",
"name": "Binding from Application Entitlement my_entitlement_name for app 6caecb97-535c-4615-b388-5ca06bf8809c #0 to Group whatever-team",
"pk": "25ed2ec847bd409589f941e00fe94157"
}
`
But when we remove a Group we get:
` "model": {
"app": "authentik_policies",
"model_name": "policybinding",
"name": "Binding from PolicyBindingModel 31fe2e31-a503-41c0-a597-5a04f6afd578 #0 to Group whatever-team",
"pk": "25ed2ec847bd409589f941e00fe94157"
}
`
Missing both the app and entitlement name, so we are not able to produce an audit report.