kernel: microcode in every initramfs through mkinitcpio's microcode hook (issue 1977)

Declares amd-ucode and intel-ucode, the drop-in /etc/mkinitcpio.conf.d/mesh-microcode.conf, the
initramfs script and mesh-kernel-initramfs.service; kernel_boot answers the running revision and
whether the images were built with the drop-in. Tests: 1977/AC1-AC5.

Builds: L1, L2, L3, L4, L5 (issue 1977 note 2)

modules/kernel/files/mesh-microcode.conf

@@ -0,0 +1,8 @@
+# Module kernel, novox/hq issue 1977. mkinitcpio reads this after /etc/mkinitcpio.conf: it adds the microcode
+# hook, which puts the CPU's current microcode (amd-ucode, intel-ucode) at the front of every initramfs, so
+# every boot entry loads it, the default one too. HOOKS that name it already are left as they are.
+# Written by the mesh; change the module.
+case "$(declare -p HOOKS)" in
+*'"microcode"'*) ;;
+*) HOOKS+=(microcode) ;;
+esac