build: add support for local config builds via act (#3124)

Adds support for building the firmware in the config-repo locally via
[act](https://github.com/nektos/act).

Linux example command:
```shell
act --artifact-server-path $PWD/.artifacts
```

MacOS (M2) example command:
```shell
act --artifact-server-path $PWD/.artifacts \
--container-architecture \
linux/amd64 --container-daemon-socket -

.github/workflows/build-user-config.yml

@@ -49,6 +49,12 @@ jobs:
       fail-fast: false
       matrix: ${{ fromJson(needs.matrix.outputs.build_matrix) }}
     steps:
+      - name: Act Workaround # https://github.com/nektos/act/issues/973
+        if: ${{ env.ACT }}
+        run: |
+          apt-get update && apt-get install -y curl unzip
+          curl -fsSL https://deb.nodesource.com/setup_22.x | bash && apt install -y nodejs
+
       - name: Checkout
         uses: actions/checkout@v4