Add more linters to improve code readability (#19989)

Add nakedret, unconvert, wastedassign, stylecheck and nolintlint linters to improve code readability

- nakedret - https://github.com/alexkohler/nakedret - nakedret is a Go static analysis tool to find naked returns in functions greater than a specified function length.
- unconvert - https://github.com/mdempsky/unconvert - Remove unnecessary type conversions
- wastedassign - https://github.com/sanposhiho/wastedassign -  wastedassign finds wasted assignment statements.
- notlintlint -  Reports ill-formed or insufficient nolint directives
- stylecheck - https://staticcheck.io/docs/checks/#ST - keep style consistent
  - excluded: [ST1003 - Poorly chosen identifier](https://staticcheck.io/docs/checks/#ST1003) and [ST1005 - Incorrectly formatted error string](https://staticcheck.io/docs/checks/#ST1005)

routers/web/feed/convert.go

@@ -71,7 +71,7 @@ func feedActionsToFeedItems(ctx *context.Context, actions models.ActionList) (it
 	for _, act := range actions {
 		act.LoadActUser()
 
-		content, desc, title := "", "", ""
+		var content, desc, title string
 
 		link := &feeds.Link{Href: act.GetCommentLink()}
 
@@ -246,7 +246,7 @@ func feedActionsToFeedItems(ctx *context.Context, actions models.ActionList) (it
 			Content: content,
 		})
 	}
-	return
+	return items, err
 }
 
 // GetFeedType return if it is a feed request and altered name and feed type.