Cursor - Model.id is never set

**Describe the bug**
A clear and concise description of what the bug is.

`cursor/Model.id` is never set.

Cursors check if `BlinkMsg`s have the same id as the Model, but it's never set, thus every blink msg is for every Model

**Source Code**
Please include source code if needed to reproduce the behavior.

https://github.com/charmbracelet/bubbles/blob/601039139c06ee7ca33a0190a928e3f444e1714e/cursor/cursor.go#L74

https://github.com/charmbracelet/bubbles/blob/601039139c06ee7ca33a0190a928e3f444e1714e/cursor/cursor.go#L191