armbian-next: artifacts: firmware/rootfs and actual usage of artifacts during image build

- artifacts: introduce `ARTIFACT_IGNORE_CACHE=yes`
- artifacts: introduce `DONT_BUILD_ARTIFACTS`, list of artifacts that if not found cached, fail the build
- kernel_package_source() is no more
- a long dissertation about kernels, families, and the universe
- artifacts: actually use rootfs artifact for image build
- artifacts: detangle via artifact_base_dir
- artifacts: rootfs: use folders in artifact_name; include cache_type
- artifacts: some cleanups / validations
- rootfs artifact; drop old rootfs cli
- artifacts: new CLI shortcuts; remove old firmware CLI
- artifacts: full firmware & usage
- use firmware artifacts in image build and install its debs
- kernel artifact sans legacy; use tmpdir for .deb target for all packages
- legacy artifact versions is no more; pack/unpack now in common obtain;
- artifacts: uboot: cleanup legacy renaming, use artifact version directly
- artifacts: add firmware (small) artifact
- deploy uboot to loop from artifact; allow tty to artifact; todos for cleaning
- fixes, kernel dtb/headers conditional; remove `.git` from Makefile url; use mapfile for finding files to hash
  - completely remove KERNEL_HAS_WORKING_HEADERS_FULL_SOURCE and `kernel_package_callback_linux_headers_full_source()`
  - don't use realpath for artifact_file_relative
  - curb some warnings
  - fix: only install headers & dtbs if such exist
- kernel .config hook modification hash versioning
- OCI_TARGET_BASE vs per-artifact defaults; only deploy to remote from CLI with OTB
- artifact revolver & installing into image
  - add artifact_map_packages and artifact_map_debs dicts
  - revolver accumulates all info
  - REPOSITORY_INSTALL is no more (for uboot/kernel, later others)
  - rename `VER` to `IMAGE_INSTALLED_KERNEL_VERSION`

lib/functions/rootfs/apt-install.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-apt_purge_unneeded_packages() {
+function apt_purge_unneeded_packages() {
 	# remove packages that are no longer needed. rootfs cache + uninstall might have leftovers.
 	display_alert "No longer needed packages" "purge" "info"
 	chroot_sdcard_apt_get autoremove
@@ -8,9 +8,7 @@ apt_purge_unneeded_packages() {
 
 # this is called:
 # 1) install_deb_chroot "${DEB_STORAGE}/somethingsomething.deb" (yes, it's always ${DEB_STORAGE})
-# 2) install_deb_chroot "linux-u-boot-${BOARD}-${BRANCH}" "remote" (normal invocation, install from repo)
-# 3) install_deb_chroot "linux-u-boot-${BOARD}-${BRANCH}" "remote" "yes" (install from repo, then also copy the WHOLE CACHE back to DEB_STORAGE)
-install_deb_chroot() {
+function install_deb_chroot() {
 	local package="$1"
 	local variant="$2"
 	local transfer="$3"