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.

Author: per1234

.github/workflows/compile-examples.yml

@@ -37,6 +37,7 @@ jobs:
         - examples/WiFiWebClient
         - examples/WiFiWebClientRepeating
         - examples/WiFiWebServer
+      SKETCHES_REPORTS_PATH: sketches-reports
 
     strategy:
       fail-fast: false
@@ -80,3 +81,11 @@ jobs:
           sketch-paths: |
             ${{ env.UNIVERSAL_SKETCH_PATHS }}
             ${{ matrix.firmwareUpdater-sketch-paths }}
+          enable-deltas-report: true
+          sketches-report-path: ${{ env.SKETCHES_REPORTS_PATH }}
+
+      - name: Save memory usage change report as artifact
+        uses: actions/upload-artifact@v2
+        with:
+          name: ${{ env.SKETCHES_REPORTS_PATH }}
+          path: ${{ env.SKETCHES_REPORTS_PATH }}

.github/workflows/report-size-deltas.yml

@@ -0,0 +1,14 @@
+on:
+  schedule:
+    - cron:  '*/5 * * * *'
+
+jobs:
+  report:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Comment size deltas reports to PRs
+        uses: arduino/report-size-deltas@main
+        with:
+          # The name of the workflow artifact created by the "Compile Examples" workflow
+          sketches-reports-source: sketches-reports