[chore] Move local account settings to separate db table (#2770)

* [chore] Move local account settings to separate database model

* don't use separate settings_id

internal/processing/account/rss.go

@@ -64,7 +64,7 @@ func (p *Processor) GetRSSFeedForUsername(ctx context.Context, username string)
 	}
 
 	// Ensure account has rss feed enabled.
-	if !*account.EnableRSS {
+	if !*account.Settings.EnableRSS {
 		err = gtserror.New("account RSS feed not enabled")
 		return nil, never, gtserror.NewErrorNotFound(err)
 	}