Add Azure Linux 4.0 support

[vinceaperri]

• Download and test azl4 test image in functional and vm test workflows (core-efi only, legacy option unavailable)

• Add azl4 to distribution-support table (all yes except --package-snapshot-time and os.packages.shapshotTime: the package snapshot time APIs require tdnf but azl4 uses dnf)

• Add azl4 to the developer guide (no link because it hasn't been released yet)

• Add azl4 to the README as a supported input image

• Add azl4 vm tests (equivalents of the existing azl3 vm tests)

  • test_min_change_efi_azl4_iso_full_os_output
  • test_min_change_efi_azl4_iso_bootstrap_output
  • test_min_change_efi_azl4_qcow_output
  • test_create_image_efi_qcow_output_azl4

• Add azl4 to:

  • azureLinuxDistroHandler.GetTargetOs()
  • newAzureLinuxDistroHandler()z
  • NewDistroHandlerFromTargetOs()
  • getFileSystemOptions()
  • GetInstalledTargetOs()
  • TestCreateImageRaw()
  • TestCreateImageBtrfs()
  • TestCreateImageRawNoTar()
  • TestCreateImage_OutputImageFileAsRelativePath()
  • TestValidateCreateImageOutput_AcceptsValidPaths()
  • TestValidateCreateImageConfig_EmptyPackagestoInstall()
  • TestBootCustomizer*() family of tests

• Create baseImageAzureLinuxCoreEfiAll var containing both azl3 and azl4 core-efi images, to migrate all tests that only test testBaseImageAzl3CoreEfi to test baseImageAzureLinuxCoreEfiAll as well (enabling additional tests)

  • Notes:
    • TestCustomizeImagePackagesUrlSource is always skipped for azl4, since cloud-native-azl4.repo but hasn't yet been added yet, as the repository does not yet exist for azl4.
    • TestCustomizeImagePackagesSnapshotTime, TestCustomizeImagePackagesCliSnapshotTimeOverridesConfigFile, and TestCustomizeImagePackagesSnapshotTimeWithoutPreviewFlagFails are explicitly skipped for azl4, since it doesn't currently support this feature. The feature (added to azl3's tdnf by Microsoft but not upstreamed) would need to be ported to azl4's dnf before we could add support.

• Add azl4 core-efi image to baseImageAzureLinuxAll (enables a ton of tests that currently test azl3)

• Split functional tests for AZL in Build (dev) workflow into 4 and 3+2 to enable azl4 testing in main builds

• No longer skip TestCustomizeImageOverlaysSELinux/AzureLinux3CoreEfi

• Review notes:

  • New configs were created for azl4 only when changes were backwards-incompatible with azl3 (e.g. kernel version differences)
  • skip_if_unavailable=False is set when refreshing azl4 package metadata to match tdnf behavior in azl3, which errors if repo isn't available (this is explicitly tested for in TestCustomizeImagePackagesBadRepo)
  • We check for systemd-boot-unsigned instead of systemd-boot in validateUkiDependencies() for azl4 because it hasn't been released yet (when released, will converge on using systemd-boot)
  • Switching (again) from unzip to wget in tests since azl4 has unzip installed

• Follow up tasks:

  • Add package snapshot time support to AZL4's dnf (enables package snapshot time feature)
  • Add cloud-native-azl4.repo when it becomes available (enables additional test coverage)
  • Remove systemd-boot-unsigned for azl4 when systemd-boot becomes available (enables secure boot)
  • Upstream ukify patch (see Patch ukify (AZL3) step in the pipelines)
  • Enable TestCustomizeImageMultiKernel for AZL4 when its repos contain multiple kernels (add the newer kernel to multikernel-azl4.yaml)
  • Remove the workaround to remove grub2-efi-x64/aa64 on AZL4 after upgrade to shim 16.1+ (Fedora 44+)
  • Onboard a bare-metal image for azl4 (when available)
  • Add support for ISO and PXE-* outputs

[liulanze]

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