Add Shell check CI testing (#2033)

* using bash-based shellcheck instead of GitHub Marketplace action
* add color shellcheck option

.github/workflows/testpr.yml

@@ -1,9 +1,21 @@
-name: build pr kernel
+name: test pull request
 # This workflow is triggered on pushes to the repository.
 on: [pull_request]
 
 jobs:
-  build:
+  shellcheck:
+    name: shellcheck
+    runs-on: ubuntu-latest
+    steps:
+       - name: Checkout repository
+         uses: actions/checkout@v2
+       - name: Environment variables
+         run: sudo -E bash -c set
+       - name: Install required packages
+         run: sudo apt-get install shellcheck
+       - name: "lint libraries via shellcheck"
+         run: shellcheck --color -x -s bash lib/*.sh && echo "shellcheck lib/*.sh - OK";
+  build_sbc_kernel:
     name: Compile changed kernel
     # This job runs on self hosted Linux machine, with public label
     runs-on: [self-hosted, public]
@@ -11,6 +23,9 @@ jobs:
 #      - uses: rokroskar/workflow-run-cleanup-action@v0.2.2
 #        env:
 #          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+      - name: fix sudo ownership
+        run: |
+          sudo chown -R $(whoami) build
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0