linux: Fix IME panel position while enumerating input methods (#12495)

Release Notes:

- N/A

This updates the IME position every time the selection changes, this is
probably only useful when you enumerate languages with your IME.

TODO:
- ~There is a rare chance that the ime panel is not updated because the
window input handler is None.~
- ~Update IME panel in vim mode.~
- ~Update IME panel when leaving Buffer search input.~

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Co-authored-by: Mikayla Maki <mikayla@zed.dev>