Optimize SQLite3 access. Mainly separate read access from write access.

Based on tips from https://archive.is/Xfjh6#selection-257.0-278.0

persistence/playlist_repository_test.go

@@ -3,6 +3,7 @@ package persistence
 import (
 	"context"
 
+	"github.com/navidrome/navidrome/db"
 	"github.com/navidrome/navidrome/log"
 	"github.com/navidrome/navidrome/model"
 	"github.com/navidrome/navidrome/model/criteria"
@@ -17,7 +18,7 @@ var _ = Describe("PlaylistRepository", func() {
 	BeforeEach(func() {
 		ctx := log.NewContext(context.TODO())
 		ctx = request.WithUser(ctx, model.User{ID: "userid", UserName: "userid", IsAdmin: true})
-		repo = NewPlaylistRepository(ctx, getDBXBuilder())
+		repo = NewPlaylistRepository(ctx, NewDBXBuilder(db.Db()))
 	})
 
 	Describe("Count", func() {