kernel/uboot/atf: introduce kernel-patch, uboot-patch, atf-patch, uboot-config, kernel-config CLI commands; enhanced manual patching; block deprecated ways

- all interactive commands now **don't build the artifact** anymore; just patches/.configs are produced and then build ends
  - user is required to put the produced patches in the right place and build again, for full consistency
- split ATF and U-BOOT manual patching process; use CLI command `atf-patch` to patch ATF, and `uboot-patch` to patch u-boot
- non-interactive artifact builds are now 100% sans-stdin
- introduce `uboot-config` CLI command; still experimental, only produces a defconfig and not a patch
- reworked `userpatch_create()` to be (hopefully) more useful:
  - detects a previous patch and offers to apply it before continuing
  - enters a loop showing the diff, and only proceeds when user indicates he's happy with the patch
  - produces `mbox`-formatted patches via `format-patch` and standard Armbian parameters
  - uses MAINTAINER and MAINTAINERMAIL instead of git configuration (so it works in containers)
- don't allow image builds with any patching or configuring _at all_ (it has been deprecated with a warning for months already, and results are inconsistent)

lib/functions/compilation/kernel.sh

@@ -54,6 +54,12 @@ function compile_kernel() {
 		return 0
 	fi
 
+	# Stop after creating patches.
+	if [[ "${CREATE_PATCHES}" == yes ]]; then
+		display_alert "Stopping after creating kernel patch" "" "cachehit"
+		return 0
+	fi
+
 	# patching worked, it's a good enough indication the git-bundle worked;
 	# let's clean up the git-bundle cache, since the git-bare cache is proven working.
 	LOG_SECTION="kernel_cleanup_bundle_artifacts" do_with_logging do_with_hooks kernel_cleanup_bundle_artifacts
@@ -69,6 +75,12 @@ function compile_kernel() {
 
 	kernel_config # has it's own logging sections inside
 
+	# Stop after configuring kernel.
+	if [[ "${KERNEL_CONFIGURE}" == yes ]]; then
+		display_alert "Stopping after configuring kernel" "" "cachehit"
+		return 0
+	fi
+
 	# build via make and package .debs; they're separate sub-steps
 	kernel_prepare_build_and_package # has it's own logging sections inside