build.sh: Add a flag make a raw edl flashable image package

Description

build.sh: Add a flag make a raw edl flashable image package

Issue(s)

https://gitlab.e.foundation/e/devices/backlog/-/issues/90

Test environment

• Set CI branch to 90devices-FP4_edl_image-test
• Make a build with the following parameters:
  • DEVICES: FP4
  • BRANCH_NAME: v1-r

Job: https://gitlab.e.foundation/e/priv/os/build/-/jobs/285528

Test procedures

• Look for the presence of the EDL-*.zip artifact
• Download EDL-*.zip artifact
• Unzip and check for presence of super.raw.img
• file super.raw.img to confirm it is a raw image.

Technical details

• For use on the flash station
• This is only for convenience sake, since unsparsing a super image on the Raspberry Pi isnt possible

Check list

• Self review
• Test procedure explained
• Tested on fresh install
• Tested applied as an update
• License
• Internal documentation
• User documentation