(DOCSP-35186): C++: Break out test suite workflows (#3145)

## Pull Request Info

Jira ticket: https://jira.mongodb.org/browse/DOCSP-35298

There is no good reason the Sync tests shouldn't run in the existing
workflow. When I run the Sync tests by themselves, they work. So I guess
I'll break them out into separate workflows, which will speed them up,
anyway, so they can run in parallel instead of serially.

Presumably this will also resolve the failing Sync tests, since they
worked fine in #3142 when I broke them out separately.

### Review Guidelines


[REVIEWING.md](https://github.com/mongodb/docs-realm/blob/master/REVIEWING.md)

.github/workflows/c++_asymmetric.yml

@@ -0,0 +1,23 @@
+name: C++ Asymmetric Sync Example Tests
+
+on:
+  pull_request:
+    paths:
+      - "examples/cpp/asymmetric/**"
+
+jobs:
+  tests:
+    runs-on: macOS-12
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Build
+        run: |
+          cd examples/cpp/asymmetric
+          mkdir build && cd build
+          cmake ..
+          cmake --build .
+      - name: Test
+        run: |
+          cd examples/cpp/asymmetric/build
+          ./examples-asymmetric

.github/workflows/c++_local.yml

@@ -0,0 +1,23 @@
+name: C++ Local Example Tests
+
+on:
+  pull_request:
+    paths:
+      - "examples/cpp/local/**"
+
+jobs:
+  tests:
+    runs-on: macOS-12
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Build
+        run: |
+          cd examples/cpp/local
+          mkdir build && cd build
+          cmake ..
+          cmake --build .
+      - name: Test
+        run: |
+          cd examples/cpp/local/build
+          ./examples-local

.github/workflows/c++_sync.yml

@@ -0,0 +1,23 @@
+name: C++ Sync Example Tests
+
+on:
+  pull_request:
+    paths:
+      - "examples/cpp/sync/**"
+
+jobs:
+  tests:
+    runs-on: macOS-12
+
+    steps:
+      - uses: actions/checkout@v3
+      - name: Build
+        run: |
+          cd examples/cpp/sync
+          mkdir build && cd build
+          cmake ..
+          cmake --build .
+      - name: Test
+        run: |
+          cd examples/cpp/sync/build
+          ./examples-sync