There apparently is some amdgpu/radv bug that rendering with
multisample anti-aliasing (MSAA) results in a crash when the bounds
of a triangle list exceed 1024px, which in Zed happens with the default
buffer font size when you select a line with more than 144 characters.

This crash has been reported as #26143.

This commit introduces a workaround: you can set the
ZED_PATH_SAMPLE_COUNT=0
environment variable to disable MSAA and the error message we print
when a GPU crash is encountered with radv now suggests trying this
environment
variable as a workaround and links the respective issue.

Sidenote: MSAA was introduced in
f08b1d78ec1655a56b07c5efcd74d225d2a4b7d5
so you didn't run into this driver bug with versions < 0.173.8.

Release Notes:

- Added a workaround for an AMD Linux driver bug that causes Zed to
crash when selecting long lines.