Add OndselSolver as git submodule

also update github actions to pull submodules

.github/workflows/sub_lint.yml

@@ -199,6 +199,8 @@ jobs:
     steps:
       - name: Check out code
         uses: actions/checkout@v3
+        with:
+          submodules: true
       - name: Make needed directories, files and initializations
         id: Init
         run: |