Rename artifacts to use os-arch-name pattern (#910)

This moves all artifacts for a single os/arch combo together in the
GitHub Actions page, making it easier to download relevant artifacts
when reproducing a build.

Author: Steelskin

.github/workflows/build-toolchain.yml

@@ -922,12 +922,12 @@ jobs:
     steps:
       - uses: actions/download-artifact@v4
         with:
-          name: installer-amd64
+          name: Windows-amd64-installer
           path: ${{ github.workspace }}/tmp/amd64
 
       - uses: actions/download-artifact@v4
         with:
-          name: installer-arm64
+          name: Windows-arm64-installer
           path: ${{ github.workspace }}/tmp/arm64
 
       - name: Create Release