Select account in account list if edited

Before: After a rightclick -> "Modify Account" on an account in the
roster the preferences of the account are shown but the account is not
selected in the account list.
After: account will be selected in the account list too

gajim/accounts_window.py

@@ -225,6 +225,7 @@ class AccountsWindow(Gtk.ApplicationWindow):
     def select_account(self, account):
         for row in self.account_list.get_children():
             if row.get_child().account == account:
+                self.account_list.select_row(row)
                 self.account_list.emit('row-activated', row)
                 break