make delete for all true as default and add padding between checkbox and label

1. Currently, in private chats, when deleting a message, the "delete for the other user too" checkbox is NOT ticked by default. Telegram desktop does have this box ticked by default. I admit, most of the time I tend to forget to tick that box. So lets make it ticked by default.

2. the margin between the checkbox and the label is too small. The label is squeezed to the checkbox. So I increase that margin a tiny bit. Screenshots below.