CI: move grabpl build-plugins from grabpl to grafana (#53071)

* add grabpl command to build internal plugins

* grabpl build-plugins -> ./bin/build build-plugins

pkg/build/cmd/buildinternalplugins.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"context"
+	"log"
+	"path/filepath"
+
+	"github.com/grafana/grafana/pkg/build/config"
+	"github.com/grafana/grafana/pkg/build/errutil"
+	"github.com/grafana/grafana/pkg/build/plugins"
+	"github.com/grafana/grafana/pkg/build/syncutil"
+	"github.com/urfave/cli/v2"
+)
+
+func BuildInternalPlugins(c *cli.Context) error {
+	cfg := config.Config{
+		NumWorkers: c.Int("jobs"),
+	}
+
+	const grafanaDir = "."
+	metadata, err := config.GetMetadata(filepath.Join("dist", "version.json"))
+	if err != nil {
+		return err
+	}
+	verMode, err := config.GetVersion(metadata.ReleaseMode)
+	if err != nil {
+		return err
+	}
+
+	log.Println("Building internal Grafana plug-ins...")
+
+	ctx := context.Background()
+
+	p := syncutil.NewWorkerPool(cfg.NumWorkers)
+	defer p.Close()
+
+	var g *errutil.Group
+	g, ctx = errutil.GroupWithContext(ctx)
+	if err := plugins.Build(ctx, grafanaDir, p, g, verMode); err != nil {
+		return cli.Exit(err.Error(), 1)
+	}
+	if err := g.Wait(); err != nil {
+		return cli.Exit(err.Error(), 1)
+	}
+
+	if err := plugins.Download(ctx, grafanaDir, p); err != nil {
+		return cli.Exit(err.Error(), 1)
+	}
+
+	log.Println("Successfully built Grafana plug-ins!")
+
+	return nil
+}