gpui: Add example for `uniform_list` (#17421)

GPUI: Add example for `uniform_list`

- Added example for `uniform_list`
  - Run `cargo run --example uniform_list`  to fire up the example
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https://github.com/user-attachments/assets/bb554fbc-c097-4ce5-8077-782dc4c5c398

Release Notes:

- N/A


https://github.com/user-attachments/assets/bb554fbc-c097-4ce5-8077-782dc4c5c398

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Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>