Stickers: keyboard convenience when sending a sticker

Let's say you want to send a busy Sheltie sticker. You click on the ```☺``` (“Show Stickers”) button to open the dialog. Then there are two issues:

- [ ] Typing right away to search for a sticker does not work. You *must* click on the search edit field to type something. I suggest the search field should be focused automatically.
- [ ] After typing something (see screenshot below) there's no way to send the sticker using the keyboard, even if there's only one sticker left in the list. Pressing `Enter` does nothing, I tried hitting arrows and even `TAB` but with no expected result. I think if there's only one sticker left then it should be possible to send it using `Enter`.