[mic][iso] generate PXE-bootable ISO images.

[gmileka]

Merge Checklist

All boxes should be checked before merging the PR (just tick any boxes which don't apply to this PR)

• [x] The toolchain has been rebuilt successfully (or no changes were made to it)
• [x] The toolchain/worker package manifests are up-to-date
• [x] Any updated packages successfully build (or no packages were changed)
• [x] Packages depending on static components modified in this PR (Golang, *-static subpackages, etc.) have had their Release tag incremented.
• [x] Package tests (%check section) have been verified with RUN_CHECK=y for existing SPEC files, or added to new SPEC files
• [x] All package sources are available
• [x] cgmanifest files are up-to-date and sorted (./cgmanifest.json, ./toolkit/scripts/toolchain/cgmanifest.json, .github/workflows/cgmanifest.json)
• [x] LICENSE-MAP files are up-to-date (./LICENSES-AND-NOTICES/SPECS/data/licenses.json, ./LICENSES-AND-NOTICES/SPECS/LICENSES-MAP.md, ./LICENSES-AND-NOTICES/SPECS/LICENSE-EXCEPTIONS.PHOTON)
• [x] All source files have up-to-date hashes in the *.signatures.json files
• [x] sudo make go-tidy-all and sudo make go-test-coverage pass
• [x] Documentation has been updated to match any changes to the build system
• [x] Ready to merge

---

Summary

This changes updates the Azures Linux Image Customizer to emit iso images that are PXE-ready. The changes include:

• interface:
  • configuration: new configuration to specify the download url for the iso.
  • command-line: new parameter to export the iso image contents into a folder for easier deployment unto a pxe server.
• implementation:
• implemented the above interface changes.
• extended the set of parameters that must be saved between runs to include the new pxe parameters.
• updated the code to emit a pxe grub.cfg and a pxe dracut config.
• update the dracut package to include an additional download script that will be triggered in the pxe scenario.

Change Log

• [mic][iso] generate PXE-bootable ISO images.
• Fix tests
• Fix azl2 tests

Does this affect the toolchain?

NO

Associated issues

• #9293

Links to CVEs

• n/a

Test Methodology

• Deploy a PXE server on the network.
• Create an iso and specify the new --output-pxe-artifacts-dir
• Deploy the iso to the pxe server and boot a PXE client.
• Deploy the artifacts folder contents to a the pxe server and boot a PXE client.
• Tested iso-to-iso customization and ensured kernel parameters are augmented.