Report changes in memory usage that would result from merging a PR

On creation or commit to a pull request, a report of the resulting change in memory usage of the examples will be
commented to the PR thread.

.github/workflows/compile-examples.yml

@@ -23,6 +23,9 @@ jobs:
     name: ${{ matrix.board.fqbn }}
     runs-on: ubuntu-latest
 
+    env:
+      SKETCHES_REPORTS_PATH: sketches-reports
+
     strategy:
       fail-fast: false
 
@@ -48,3 +51,12 @@ jobs:
             - name: WiFi101
           sketch-paths: |
             - examples
+          enable-deltas-report: true
+          sketches-report-path: ${{ env.SKETCHES_REPORTS_PATH }}
+
+      - name: Save sketches report as workflow artifact
+        uses: actions/upload-artifact@v2
+        with:
+          if-no-files-found: error
+          path: ${{ env.SKETCHES_REPORTS_PATH }}
+          name: ${{ env.SKETCHES_REPORTS_PATH }}