Added gen-salt.sh to generate and get a SetCredentialEncrypted= to put in a systemd service.

tools/gen-salt.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/sh
+
+if [[ $1 ]]; then
+    char_num=$1;
+else
+    char_num=64;
+fi
+
+cat /dev/urandom | tr -dc 'a-zA-Z0-9!@#$%^&*' | fold -w $char_num | head -n 1 | systemd-creds encrypt -p - /tmp/salt
+
+cat /tmp/salt
+rm /tmp/salt