Writing profiles.el was borderline unreadable.
`doom-profiles-autodetect` was effectively just reading in the entire
file: accepting the paths we want in the profile as individual args and
putting them together on the Emacs side is easy enough.
Accidentally fixes a bug: `user-emacs-directory` should end in a
directory separator. We now get the right value for free by using the
path we're running Doom CLI out of.
doom-profile-data-dir is for the current profile, naming it
"profiles" (plural) made no sense.
Also move the loader into its own subdir so it's more obvious what the
two init.29.elc files are.
