SDK - Report available provider types, names, and descriptions

[independentid]

This enhancement is to enable Policy-Orchestrator Admin UI to automatically render available provider integrations. The
discovery call should return an array or map of ProviderTypes as follows:

type ProviderType struct {
Type string // type code corresponding to the provider type code used in the SDK
Short string // a short name typically used on a button
Description string // a long name which can be used in help text.
Capabilities []string // TBD... a set of capabilities that the provider has: e.g. reconcile, schema, byPolicy
}

TBD.... each capability above indicates an interface that is supported by the provider. For example, because AVP updates policy by id (byPolicy), a reconcile function is needed to determine the necessary CRUD operation needed to update a set of policies.

Other questions: do we need to expose whether a provider is Virtual RBAC, Syntax (GCP Bind, Cedar), or IDQL (HexaOPA)?