Conduct performance audit of Sass @import versus @use for codebase

[joshblack]

We've been heavily considering transitioning over to Sass Modules (@use), in part because it seemed like it would improve our compilation time for projects using our Sass files.

This issue is to conduct a rough performance audit of our current Sass codebase with sass-loader and @import and compare it to a converted codebase with Sass Modules.

[joshblack]

Baseline with sass-loader and sass implementation with no Carbon styles

Cold start
56533ms

Recompilation
829ms
619ms
767ms

With sass-loader and @import

Cold start
138502ms

Recompilation
50538ms
54899ms
55997ms

Average: 53808ms

With sass-loader and sass implementation

Cold start
95193ms

Recompilation
42531ms
45316ms
40227ms

Average: 42691.33ms

[joshblack]

With sass-loader, sass implementation, and @use

Cold start
57257ms

Recompilation
3397ms
2594ms
3236ms

Average
~3075ms