This PR fixes a small issue I noticed with resize cursors. The
column/row resize cursors were missing and in a few places we were using
`ew-resize` and `ns-resize` even though the documentation mentions
`col-resize` and `row-resize`.

Finally updated the panes in the workspace to use the new column/row
resize cursors.

Before:

![Screenshot_20240505_111515](https://github.com/zed-industries/zed/assets/829535/50f28a1b-33e2-431a-8fc8-5048d89c8f7b)

![Screenshot_20240505_111521](https://github.com/zed-industries/zed/assets/829535/45856f7e-4ca9-4b39-9f8c-144934e9d41e)

After:

![Screenshot_20240505_110606](https://github.com/zed-industries/zed/assets/829535/2b247ec1-44ef-4293-87b3-7fda4b2ebf8f)

![Screenshot_20240505_110611](https://github.com/zed-industries/zed/assets/829535/b558e1ce-3e08-4de3-8a11-6a80184d84fe)



Release Notes:

- Added column/row resize cursor styles to GPUI
- Fixed the existing references that were incorrectly using `ew-resize`
for column resize and `ns-resize` for row resize
- Updated panes to use column/row resize cursors instead on `ew-resize`
and `ns-resize`

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