Plugins: Refactor loader + finder to support multiple sourcing methods (#64735)

* it's cdn time

* tidy body closing

* auto signed

* fix close

* update log name

* remove comments

pkg/plugins/manager/sources/ifaces.go

@@ -6,6 +6,6 @@ import (
 	"github.com/grafana/grafana/pkg/plugins"
 )
 
-type Resolver interface {
+type Registry interface {
 	List(context.Context) []plugins.PluginSource
 }