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/store/host.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.27.1
-// 	protoc        v3.15.8
+// 	protoc        v3.17.3
 // source: controller/storage/host/plugin/store/v1/host.proto
 
 // Package store provides protobufs for storing types in the plugin host
@@ -56,8 +56,8 @@ type HostCatalog struct {
 	// @inject_tag: `gorm:"default:null"`
 	Version uint32 `protobuf:"varint,8,opt,name=version,proto3" json:"version,omitempty" gorm:"default:null"`
 	// attributes is a jsonb formatted field.
-	// @inject_tag: `gorm:"default:null"`
-	Attributes []byte `protobuf:"bytes,9,opt,name=attributes,proto3" json:"attributes,omitempty" gorm:"default:null"`
+	// @inject_tag: `gorm:"not_null"`
+	Attributes []byte `protobuf:"bytes,9,opt,name=attributes,proto3" json:"attributes,omitempty" gorm:"not_null"`
 }
 
 func (x *HostCatalog) Reset() {
@@ -184,8 +184,8 @@ type HostSet struct {
 	// @inject_tag: `gorm:"default:null"`
 	Version uint32 `protobuf:"varint,7,opt,name=version,proto3" json:"version,omitempty" gorm:"default:null"`
 	// attributes is a byte field containing marshaled JSON data
-	// @inject_tag: `gorm:"default:null"`
-	Attributes []byte `protobuf:"bytes,8,opt,name=attributes,proto3" json:"attributes,omitempty" gorm:"default:null"`
+	// @inject_tag: `gorm:"not_null"`
+	Attributes []byte `protobuf:"bytes,8,opt,name=attributes,proto3" json:"attributes,omitempty" gorm:"not_null"`
 	// preferred_endpoints stores string preference values
 	// @inject_tag: `gorm:"-"`
 	PreferredEndpoints []string `protobuf:"bytes,9,rep,name=preferred_endpoints,json=preferredEndpoints,proto3" json:"preferred_endpoints,omitempty" gorm:"-"`