Github action runs on job matrix now for parallel operation (both build and check) (#1202)

* Build matrix for parallel jobs

.github/workflows/main.yml

@@ -1,20 +1,8 @@
-name: Continuous Integration
+name: Continuous Integration (Legacy serial build)
 on:
   # Triggers the workflow on push or pull request events but only for the master branch
-  push:
-    branches: [ master ]
-    paths-ignore:
-      - '**.md'
-      - '**.yml'
-      - 'version.properties'
-      
-  # Note: This is different from "pull_request". Need to specify ref when doing checkouts.
-  pull_request_target:
-    branches: [ master ]
-    paths-ignore:
-      - '**.md'
-      - '**.yml'
-
+  workflow_dispatch:
+  
 jobs:
 
   ci-check: