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/services/pluginsintegration/pipeline/discovery.go

@@ -0,0 +1,33 @@
+package pipeline
+
+import (
+	"context"
+
+	"github.com/grafana/grafana/pkg/plugins"
+	"github.com/grafana/grafana/pkg/plugins/config"
+	"github.com/grafana/grafana/pkg/plugins/manager/loader/assetpath"
+	"github.com/grafana/grafana/pkg/plugins/manager/loader/finder"
+	"github.com/grafana/grafana/pkg/plugins/manager/pipeline/bootstrap"
+	"github.com/grafana/grafana/pkg/plugins/manager/pipeline/discovery"
+	"github.com/grafana/grafana/pkg/plugins/manager/registry"
+)
+
+func ProvideDiscoveryStage(cfg *config.Cfg, pluginFinder finder.Finder, pluginRegistry registry.Service) *discovery.Discovery {
+	return discovery.New(cfg, discovery.Opts{
+		FindFunc: func(ctx context.Context, src plugins.PluginSource) ([]*plugins.FoundBundle, error) {
+			return pluginFinder.Find(ctx, src)
+		},
+		FindFilterFuncs: []discovery.FindFilterFunc{
+			func(ctx context.Context, _ plugins.Class, bundles []*plugins.FoundBundle) ([]*plugins.FoundBundle, error) {
+				return discovery.NewDuplicatePluginFilterStep(pluginRegistry).Filter(ctx, bundles)
+			},
+		},
+	})
+}
+
+func ProvideBootstrapStage(cfg *config.Cfg, signatureCalculator plugins.SignatureCalculator, assetPath *assetpath.Service) *bootstrap.Bootstrap {
+	return bootstrap.New(cfg, bootstrap.Opts{
+		ConstructFunc: bootstrap.DefaultConstructFunc(signatureCalculator, assetPath),
+		DecorateFuncs: bootstrap.DefaultDecorateFuncs,
+	})
+}