fix: add :depth field to modules

This introduces a depth field for modules so that they may dictate their
load order explicitly, it also treats depths <= -100 or >= 100 as
special depths, which will be loaded early, before their respective
doom-{before,after}-module-{init,config}-hook. This permits psuedo
modules like :core and :user modules to be treated as normal modules
without too many special cases.

This also fixes a module load order issue on Emacs 29 (#6813), caused by
emacs-mirror/emacs@4311bd0bd7, which changed the return value order of
hash-table-{keys,values} causing modules to be loaded in reverse order;
resulting in the loss of evil keybinds, among other things.

Other notable changes:
- Changes the data structure for module data caches from a list to a
  vector. Uses less memory and permits faster lookups. Also adds two
  depth fields to the front of it.
- Changes the signature of doom-module-list and doom-package-list.
- Renames doom--read-packages -> doom-packages--read for consistency
  with naming convention.
- Add doom-module-depth function.
- Adds a temporary doom-core-dir/init.el file, which is responsible for
  loading doom-*.el.

Fix: #6813
Ref: emacs-mirror/emacs@4311bd0bd7

lisp/lib/debug.el

@@ -306,7 +306,7 @@ ready to be pasted in a bug report on github."
                       collect var)))
         (modules
          ,@(or (cl-loop with lastcat = nil
-                        for (cat . mod) in (cddr (doom-module-list))
+                        for (cat . mod) in (seq-filter #'cdr (doom-module-list))
                         if (or (not lastcat)
                                (not (eq lastcat cat)))
                         do (setq lastcat cat)

lisp/lib/packages.el

@@ -154,8 +154,7 @@ each package."
                                (if (listp m)
                                    (format "%s %s" (car m) (cdr m))
                                  (format "%s" m)))
-                             (append '(:user :core)
-                                     (delete-dups (mapcar #'car modules))
+                             (append (delete-dups (mapcar #'car modules))
                                      modules)))
                    nil t nil nil))
           (module (split-string module " " t)))
@@ -173,8 +172,7 @@ each package."
         (if module
             (list (cons category module))
           (cl-remove-if-not (lambda (m) (eq (car m) category))
-                            (append '((:core) (:user))
-                                    (doom-module-list 'all))))))
+                            (doom-module-list 'all)))))
 
 ;;;###autoload
 (defun doom/bump-package (package)