[DOCUMENTATION NEEDED] [REVIEW NEEDED] feat: implement tpm sealed sshd host keys

this allows one to verify cryptographically that the initramfs has NOT been modified, and prevents attackers from doing a MITM attack or inserting a keylogger into the initramfs. the key can not be read without booting the machine, and if you modify the initramfs, the key wont be released. this implementation is somewhat sloppy, as i just need it for my desktop and server right now. even though it passes the tests, please review thoroughly before merging.