feat: Use Sass pkg importers

### Feature Description

To improve sass modules resolution Angular material should adopt pkg importers https://sass-lang.com/blog/announcing-pkg-importers/

### Use Case

We try to adopt this feature and remove `./node_modules` from sass `loadPath` but some dependencies (like `@angular/material`) continue to use direct dependency path without `pkg:` internally.

The issue names no files or tests. Start with the linked Sass pkg importers announcement and trace where Sass loadPath and Angular Material's internal dependency paths are configured. Done means Angular Material Sass imports resolve through pkg importers without requiring ./node_modules in loadPath; run the relevant repository tests after locating the configuration entry point.

Written by the indexing model from the issue text.