Fixes #4204 

![image](https://github.com/zed-industries/zed/assets/24362066/dac093e7-d8ba-4bf9-8936-748a93dbcecf)

![image](https://github.com/zed-industries/zed/assets/24362066/f836948c-a4ad-455c-a343-8bb3ce62d467)

![image](https://github.com/zed-industries/zed/assets/24362066/54310b2a-db00-4b87-9f96-a55a81be99ed)

![image](https://github.com/zed-industries/zed/assets/24362066/dd6ef78c-2bde-4808-856b-adaa28dd00d2)

Release Notes:

- Line number indicator now shows number of lines selected and a number
of selections.