armbian-next: artifacts: introduce kernel/u-boot artifacts; git ref2info; "memoizer"; some hashing

- artifacts: u-boot/kernel - pt7 - adapt legacy/artifact versions; use common `capture_rename_legacy_debs_into_artifacts()`
- artifacts: u-boot - pt6: add artifact for u-boot
  - use artifact version / reason in actual u-boot .deb if present
- artifacts: kernel - pt5: tune kernel version, refactor
- artifacts: kernel - pt4: squash unrelated bugs that show up; move `prepare_compilation_vars()` to default build
- artifacts: kernel - pt3: drivers+patches+.config hashing
  - split file hashing function from drivers-harness; fix it so filenames are relative and sorted; sort from ${SRC}, always
  - aplit prepare_kernel_config_core_or_userpatches() from `kernel_config_initialize()`
- artifacts: kernel - pt2:  memoizing git ref2info
- artifacts: kernel - pt1:  versioning

lib/functions/artifacts/artifacts-registry.sh

@@ -0,0 +1,10 @@
+function armbian_register_artifacts() {
+
+	declare -g -A ARMBIAN_ARTIFACTS_TO_HANDLERS_DICT=(
+		#["firmware"]="firmware"
+		["kernel"]="kernel"
+		["u-boot"]="uboot"
+		["uboot"]="uboot"
+	)
+
+}