test-packaging.yaml: Split build step up further

- Split build step up further
    - Dependency installation
    - Static pre-check
    - Actual package build
- Omit pkg-build installation step for jw-pkg
    Don't build and install jw-pkg official before a jw-pkg test
    build.  jw-pkg should be self-contained enough to be able to
    build itself.
Signed-off-by: Jan Lindemann <jan@janware.com>
test-packaging.yaml: Split up build step into deps, static pre-check and actual buil
Signed-off-by: Jan Lindemann <jan@janware.com>

.github/workflows/test-packaging.yaml

@@ -28,8 +28,9 @@ jobs:
           working-directory: ${{ github.event.repository.name }}
           persist-credentials: false
 
-      - name: Install build prerequisites
+      - name: Install jw-pkg from source
         shell: bash
+        if: ${{ github.event.repository.name != 'jw-pkg' }}
         run: |
           set -euxo pipefail
           export PROJECTS_DIR_REMOTE_BASE=${{ github.server_url }}
@@ -40,6 +41,13 @@ jobs:
           make -C build-jw-foss pkg-install-release-deps
           OFFLINE=true make -C build-jw-foss pkg-rebuild-reinstall
 
+      - name: Install test-build dependencies
+        shell: bash
+        run: |
+          set -euxo pipefail
+          make -C "${{ github.event.repository.name }}" pkg-manager-refresh
+          make -C "${{ github.event.repository.name }}" pkg-install-testbuild-deps
+
       - name: Run pre-build static code checks
         shell: bash
         run: |
@@ -50,8 +58,6 @@ jobs:
         shell: bash
         run: |
           set -euxo pipefail
-          make -C "${{ github.event.repository.name }}" pkg-manager-refresh
-          make -C "${{ github.event.repository.name }}" pkg-install-testbuild-deps
           make -C "${{ github.event.repository.name }}" pkg-rebuild
 
       - name: Run post-build static code checks