ref: Remove vault-password static file from repo

Instead of having the file statically (and plain-text) in the repo
itself, we simply query `pass` for it instead.

Slightly cumbersome syntax since ansible (afaik) does not allow a
similar easy variable-enabled lookup as for become passwords, so we also
whipped it into a justfile to not have to type it each time.

The command line uses cat to receive the password as a 'file' on stdin.

ansible.cfg

@@ -1,5 +1,3 @@
 [defaults]
 remote_tmp = /tmp
 inventory = inventory
-
-vault_password_file = vaultpass

justfile

@@ -0,0 +1,2 @@
+deploy:
+    pass show hosting/ansible/bob/vault-password | ansible-playbook --vault-password-file=/bin/cat site.yaml