In this PR, we no longer buffer pointer down/ups. We now batch only
`pointer_move`, `wheel`, and `pinch` events.
Batched inputs were causing text not to work on iOS. On iOS, the
keyboard is only shown if we call `focus` during the same event loop as
a user input.
### Change Type
- [x] `sdk` — Changes the tldraw SDK
- [x] `bugfix` — Bug fix
### Test Plan
1. Use text on iOS.
988dbbde28