Add PCB renders generation CI job

[apcountryman]

Add PCB renders generation CI job. The proposed design was outlined in #33.

• [ ] Add PcbDraw as a repository submodule:

  git submodule add ../PcbDraw utilities/PcbDraw

• [ ] Add PCB renders generation script (ci/generate-pcb-renders):
  • [ ] Supported options:
    • [ ] --help: See other project scripts
    • [ ] --version: See other project scripts
  • [ ] function error(): See other project scripts
  • [ ] function abort(): See other project scripts
  • [ ] function display_help_text(): See other project scripts
  • [ ] function display_version(): See other project scripts
  • [ ] function main(): See other project scripts
  • [ ] function generate_pcb_renders():

    
    local -r pcb_renders="$repository/pcb-renders"

if ! mkdir pcb_renders; then abort fi

local layouts; mapfile -t layouts < <( git -C "$repository" ls-files '*.kicad_pcb' | xargs -r -d '\n' -I '{}' find "$repository/{}" ); readonly layouts local layout_name local -r formats=( "jpg" "png" "svg" )

for layout in "${layouts[@]}"; do layout_name=$( basename "$layout" )

for format in "${formats[@]}"; do
    if ! "$repository/utilities/PcbDraw/pcbdraw/pcbdraw.py" "$layout" "$pcb_renders/$layout_name-front.$format"; then
        abort
    fi

    if ! "$repository/utilities/PcbDraw/pcbdraw/pcbdraw.py" -b "$layout" "$pcb_renders/$layout_name-back.$format"; then
        abort
    fi
done

done

- [ ] Add PCB renders generation (and archiving) CI job to `.github/workflows/ci.yml`:
```yaml
generate-pcb-renders:
    name: Generate PCB renders
    runs-on: ubuntu-20.04
    steps:
        - uses: actions/checkout@v2
          with:
              submodules: recursive
        - name: Generate PCB renders
          shell: bash
          run: ./ci/generate-pcb-renders
        - name: Archive generated PCB renders
          uses: actions/upload-artifact@v2
          with:
              name: pcb-renders
              path: pcb-renders
              retention-days: 7