No way to verify "who I am" when logged in with managed identity

We have the pod managed identity integrated but from the current cli implementation, there's no way for us to verify the identity form cli for the pod..., it's kind of doesn't really make sense ...

this is what CLI shows me when I wanted to verify `who I am` from a pod with has managed identity binded
```
bash-5.0# az account show
{
"environmentName": "AzureCloud",
"homeTenantId": "$TENANTID",
"id": "$SUBID",
"isDefault": true,
"managedByTenants": [],
"name": "$SUBNAME",
"state": "Enabled",
"tenantId": "$TENANTID",
"user": {
"assignedIdentityInfo": "MSI",
"name": "systemAssignedIdentity",
"type": "servicePrincipal"
}
}
```

This information doesn't really tell me anything so it's hard for us to automatically check the permissions

_Originally posted by @minzhang28 in https://github.com/Azure/azure-cli/issues/10439#issuecomment-598976553_