feat: add hosts-clear and hosts-init scripts for managing known_hosts

docker-rsync/hosts-clear

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+set -euo pipefail
+
+truncate -s 0 ~/.ssh/known_hosts

docker-rsync/hosts-init

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+set -euo pipefail
+
+touch ~/.ssh/known_hosts
+chmod 600 ~/.ssh/known_hosts