style: gofumpt all the things (#9829)

Literally `gofumpt -w .` from the top level dir. Guaranteed to be minor
style changes only and nothing else.

@imsodin per request?

lib/model/blockpullreorderer.go

@@ -7,10 +7,11 @@
 package model
 
 import (
+	"sort"
+
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/rand"
-	"sort"
 )
 
 type blockPullReorderer interface {