Add Packer image builds

[CoryManson]

Still WIP

• Adds automated builds using hashicorp packer & github actions
• All images build in parallel
• Opens a draft github release and adds image files with accompanying sha256 hash (This can be changed to upload the files elsewhere)
• Generates a release version based on SemVer
• Tested so far on CM4:
  • Batocera: Boots and controller works, volume untested. Comments added to batocera sources with reasons for a base image
  • RaspiOs (Latest x64 bookworm): Controller works, brightness controls works, error when start OSD service & was unable to get volume control working
• RetroPie seemed to build happily but untested so far
• I haven't spent any time testing Lakka yet but appears to behave similarly to Batocera with complicated disk partitions
• Recalbox not yet building

Example github action running: https://github.com/CoryManson/PSPi-Version-6/actions/runs/7582462967

[CoryManson]

If this ever gets merged, please squash merge :)

[CoryManson]

Have progressed about as far as I can without some input on exactly how the images are being built. Lakka has similar complications as Batocera.

Seems to require an initialization build on hardware which is fine, tried only uploading config.txt & overlays (same as batocera) which allows it to boot on hardware but the /storage partition isn't showing on a 2nd build.

Tried using the Lakka image from proton drive & it does boot and mount /storage correctly. Unsure why the packer built image won't.

Have been unable to run shell scripts so far on Batocera & Lakka with chroot, have only been able to upload files to those images which is enough for Batocera but maybe not for Lakka.

[othermod]

I'll look into this soon. Just juggling too many things over the next couple days.