If $DOOMPATH is malformed or set to a value that does not contain a
valid path to Doom's CLI library in $EMACSDIR/lisp/cli (see #7608),
bin/doom no longer functions, emitting "a subcommand is required"
errors.
This change ensures that the CLI library is always the last (implicit)
element in doom-cli-load-path, and ensures $DOOMPATH is never written to
the user's envvar file (in case they try to use bin/doom from inside a
terminal within a Doom Emacs session), which should ensure users -- at
least -- never find themselves stranded without the Doom CLI.
Fix: #7608
Co-authored-by: bpizzi <bpizzi@users.noreply.github.com>