Placeholder Plugin Providers for Repos and added testPlugin struct (#1532)

* Create minimalistic plugin map and test plugin.

* Pass secrets and attributes to the plugin when creating catalogs or sets.  Add tests for CreateSet and CreateCatalog repo methods.

* make fmt and extract out getPrivateCatalog and getCatalog helper methods.

* Exporting TestPluginServer so it can be used in the handlers.

* Keep separate persisted data from host catalogs lookups which facilitate passing it onto the plugins.

* Add TODO to merge get Catalog and get Persisted data.

* Adding tests for unimplemented being returned by the plugin.

* Use GetFields() instead of AsMap() to confirm attributes should be populated. Make clone consistent between catalog and sets.

Co-authored-by: Jeff Mitchell <jeffrey.mitchell@gmail.com>

internal/host/plugin/options.go

@@ -1,5 +1,7 @@
 package plugin
 
+import "google.golang.org/protobuf/types/known/structpb"
+
 // getOpts - iterate the inbound Options and return a struct
 func getOpts(opt ...Option) options {
 	opts := getDefaultOptions()
@@ -16,16 +18,14 @@ type Option func(*options)
 type options struct {
 	withName               string
 	withDescription        string
-	withAttributes         map[string]interface{}
-	withSecrets            map[string]interface{}
+	withAttributes         *structpb.Struct
+	withSecrets            *structpb.Struct
 	withPreferredEndpoints []string
 }
 
 func getDefaultOptions() options {
 	return options{
-		withDescription: "",
-		withName:        "",
-		withAttributes:  make(map[string]interface{}),
+		withAttributes: &structpb.Struct{},
 	}
 }
 
@@ -44,14 +44,14 @@ func WithName(name string) Option {
 }
 
 // WithAttributes provides an optional attributes field.
-func WithAttributes(attrs map[string]interface{}) Option {
+func WithAttributes(attrs *structpb.Struct) Option {
 	return func(o *options) {
 		o.withAttributes = attrs
 	}
 }
 
 // WithSecrets provides an optional secrets field.
-func WithSecrets(secrets map[string]interface{}) Option {
+func WithSecrets(secrets *structpb.Struct) Option {
 	return func(o *options) {
 		o.withSecrets = secrets
 	}