[feature request] Opt-in for automated service broker update

Issue

Every changes to a [global] service broker catalog currently requires an execution of cf update-service-broker which requires admin permissions

Context

As a CF admin

• in order to enable 3rd party service providers to update their service catalog (such as new plans, documentation fixes) in a self-service manner without giving them cloudcontroller.admin permissions
• I need to be able to opt-in for automated service broker update in cf create-service-broker and cf update-service-broker commands

This feature request aims at feature parity with K8S service catalog broker registration

A broker may resynchronize automatically or may need to be resynchronized manually. By default, brokers are resynchronized automatically based on the brokerRelistInterval global setting in Service Catalog. If a broker must be resynchronized immediately or if .spec.relistBehavior on the broker has been set to manual, then it can be resynchronized manually by incrementing .spec.relistRequests

https://github.com/kubernetes-sigs/service-catalog/blob/a204c0d26c60b42121aa608c39a179680e499d2a/pkg/apis/servicecatalog/v1beta1/types.go#L105-L123

// RelistBehavior specifies the type of relist behavior the catalog should
// exhibit when relisting ServiceClasses available from a broker.
// +optional
RelistBehavior ServiceBrokerRelistBehavior json:"relistBehavior"

// RelistDuration is the frequency by which a controller will relist the
// broker when the RelistBehavior is set to ServiceBrokerRelistBehaviorDuration.
// Users are cautioned against configuring low values for the RelistDuration,
// as this can easily overload the controller manager in an environment with
// many brokers. The actual interval is intrinsically governed by the
// configured resync interval of the controller, which acts as a minimum bound.
// For example, with a resync interval of 5m and a RelistDuration of 2m, relists
// will occur at the resync interval of 5m.
RelistDuration *metav1.Duration json:"relistDuration,omitempty"

// RelistRequests is a strictly increasing, non-negative integer counter that
// can be manually incremented by a user to manually trigger a relist.
// +optional
RelistRequests int64 json:"relistRequests"

https://hub.kubeapps.com/charts/svc-cat/catalog

Parameter	Description	Default
controllerManager.brokerRelistInterval	How often the controller should relist the catalogs of ready brokers; duration format (20m, 1h, etc)	24h
controllerManager.brokerRelistIntervalActivated	Whether or not the controller supports a --broker-relist-interval flag. If this is set to true, brokerRelistInterval will be used as the value for that flag.	true

Considered alternatives

Future support for CF permissions could allow for a specific user to be granted service broker update permission on a given service broker entity.

Start by tracing the cf create-service-broker and cf update-service-broker entry points and how they enforce admin permissions. Done means an administrator can opt in to automated service broker catalog updates, allowing providers to update their catalogs without cloudcontroller.admin access; resolve the behavior against the cited Kubernetes relist model and the permissions alternative.