Add an animation to the LSP checking indicator (#9463)

Spinner go spinny.

Extra thanks to @kvark for helping me with the shaders.



https://github.com/zed-industries/zed/assets/2280405/9d5f4f4e-0d43-44d2-a089-5d69939938e9


Release Notes:

- Added a spinning animation to the LSP checking indicator

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Co-authored-by: Dzmitry Malyshau <kvark@fastmail.com>