add github ci compile check for ascent

.github/workflows/ascent.yml

@@ -0,0 +1,29 @@
+name: 🐧 In Situ Vis with Ascent
+
+on: [push, pull_request]
+
+concurrency:
+  group: ${{ github.ref }}-${{ github.head_ref }}-insituvis
+  cancel-in-progress: true
+
+jobs:
+  ascent:
+    name: Ascent
+    runs-on: ubuntu-20.04
+    if: github.event.pull_request.draft == false
+    env:
+      CXX: g++
+      CC: gcc
+      CMAKE_PREFIX_PATH: /home/user/ascent/install-debug/lib/cmake/
+    container:
+      image: alpinedav/ascent:ascent-ubuntu-18_2021-10-23-shaba7872
+    steps:
+    - uses: actions/checkout@v2
+    - name: Configure
+      run: |
+        . ../s_env.sh && cmake -S . -B build               \
+                                    -DWarpX_ASCENT=ON      \
+                                    -DWarpX_COMPUTE=NOACC
+    - name: Build
+      run: |
+        . ../s_env.sh && cmake --build build -j 2