Allows managing the operating system image with bootc. Initial integration without a progress bar. Gated behind HHD_BOOTC=1.
The progress bar is not done for this release.
HHD_BOOTC_BRANCHES="stable:Stable,testing:Testing,unstable:Unstable" can set the rebase branches and their names. Tags should begin with the branch name, e.g., unstable-foo and be sorted alphabetically.
Full Changelog: v3.6.2...v3.7.0