Ramdisk to test the kernel in a semi-automated manner.
Some parts are based on postmarketOS ramdisk.
Accept boot command line hl_rd="word1 word2...". Currently valid words are test and shell.
If not specified, defaults to hl_rd="shell".
test causes /bin/hoolocktest to be ran
shell causes a shell to be spawned in a loop infinitely.
If test fails, a shell is spawned in a loop infinitely.
Otherwise, when the init script runs out of actions, the device is rebooted.