feat: copy dotnet examples from examples repo (#148)

* feat: copy dotnet examples from examples repo

We are in the process of moving the examples out of the old
examples repo and into the individual SDK repos.  This commit
copies the dotnet examples over; no changes.

Also copies over Pete's dependabot/examples CI work.

.github/dependabot.yml

@@ -0,0 +1,13 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+
+version: 2
+updates:
+  - package-ecosystem: "nuget" # See documentation for possible values
+    directory: "/examples" # Location of package manifests
+    schedule:
+      interval: "daily"
+    allow:
+      - dependency-name: "Momento.Sdk"

.github/workflows/ci.yaml

@@ -46,3 +46,41 @@ jobs:
         run: |
           dotnet test tests/Integration/Momento.Sdk.Incubating.Tests
         shell: bash
+
+  build_examples:
+    runs-on: ubuntu-latest
+    env:
+      # TODO: remove token stored as secret in favor of using a
+      # momento-local instance that can be spun up for testing
+      MOMENTO_AUTH_TOKEN: ${{ secrets.ALPHA_TEST_AUTH_TOKEN }}
+
+    steps:
+      - name: Setup repo
+        uses: actions/checkout@v2
+
+      - name: Set up dotnet
+        uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: "6.0.x"
+
+      - name: Run samples
+        id: validation
+        continue-on-error: true
+        run: |
+          pushd dotnet/MomentoExamples
+            dotnet build MomentoApplication
+            dotnet run --project MomentoApplication
+            dotnet build MomentoApplicationPresignedUrl
+          popd
+        shell: bash
+
+      - name: Send CI failure mail
+        if: ${{ steps.validation.outcome == 'failure' }}
+        uses: ./.github/actions/error-email-action
+        with:
+          username: ${{secrets.MAIL_USERNAME}}
+          password: ${{secrets.MAIL_PASSWORD}}
+
+      - name: Flag Job Failure
+        if: ${{ steps.validation.outcome == 'failure' }}
+        run: exit 1