Plugins: Plugins loader pipeline (#71438)

* discovery

* flesh out

* add docs

* remove unused func

* bootstrap stage

* fix docs

* update docs

* undo unnecessary changes

* add end tag

* update doc

* fix linter

* fix

* tidy

* update docs

* add class to filter func

* apply PR feedback

* fix test

pkg/plugins/manager/loader/assetpath/assetpath.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 
 	"github.com/grafana/grafana/pkg/plugins"
+	"github.com/grafana/grafana/pkg/plugins/config"
 	"github.com/grafana/grafana/pkg/plugins/pluginscdn"
 )
 
@@ -22,6 +23,10 @@ func ProvideService(cdn *pluginscdn.Service) *Service {
 	return &Service{cdn: cdn}
 }
 
+func DefaultService(cfg *config.Cfg) *Service {
+	return &Service{cdn: pluginscdn.ProvideService(cfg)}
+}
+
 // Base returns the base path for the specified plugin.
 func (s *Service) Base(pluginJSON plugins.JSONData, class plugins.Class, pluginDir string) (string, error) {
 	if class == plugins.ClassCore {