GH Actions Submod NOM Flag

[madMatchstick]

Update submodule actions for NOM to include build flag -NGEN_IS_MAIN_PROJECT

Changes

• added input is_main_project to submod lib build actions.yml - specific to Noah-OWP-Modular

Formulation Notes

• There are (3) "formulation" repos (PET, Topmodel & NOM) which currently use/build NOM as apart of testing. Therefore (ngen_integration.yaml) workflows will be defined as follows,

      - name: Build Surfacebmi
        id: submod_build_1
        uses: ./.github/actions/ngen-submod-build
        with:
          mod-dir: " extern/noah-owp-modular/"
          targets: "surfacebmi"
          is_main_project: 'ON'

Notes

Speaks to Issue #761 - but hesitant to close as there maybe more flags that I am missing outside of NOM (e.g extern/cfe/cfe/ -DNGEN=ON)?