ci/cd: centralize and bump artifact uploads

- Upgrade `actions/upload-artifact` to `v4` to address deprecation
  warnings related to Node.js 16, improving compatibility with GitHub
  runners. This resolves the following warning from the runners:
  > Node.js 16 actions are deprecated. Please update the following actions
  > to use Node.js 20: actions/upload-artifact@v3.
- Centralize the use of the `upload-artifact` action through a new
  custom action, improving maintainability and consistency across
  workflows.

.github/workflows/checks.desktop-runtime-errors.yaml

@@ -70,7 +70,7 @@ jobs:
       -
         name: Upload screenshot
         if: always() # Run even if previous step fails
-        uses: actions/upload-artifact@v3
+        uses: ./.github/actions/upload-artifact
         with:
           name: screenshot-${{ matrix.os }}
           path: screenshot.png