Introduce a `LIB_STATE_DIR` syspaths variable which defaults to `CONFIG_DIR`,
but can be individually customized during installation by specifying
`--salt-lib-state-dir` during installation. Change the default `pki_dir` to
`<LIB_STATE_DIR>/pki/master` (for the master) and `<LIB_STATE_DIR>/pki/minion`
(for the minion).