refactor: deprecate featurep! for modulep!

featurep! will be renamed modulep! in the future, so it's been
deprecated. They have identical interfaces, and can be replaced without
issue.

featurep! was never quite the right name for this macro. It implied that
it had some connection to featurep, which it doesn't (only that it was
similar in purpose; still, Doom modules are not features). To undo such
implications and be consistent with its namespace (and since we're
heading into a storm of breaking changes with the v3 release anyway),
now was the best opportunity to begin the transition.

modules/config/default/autoload/default.el

@@ -32,7 +32,7 @@ generate `completing-read' candidates."
 (defun +default/new-buffer ()
   "TODO"
   (interactive)
-  (if (featurep! 'evil)
+  (if (modulep! 'evil)
       (call-interactively #'evil-buffer-new)
     (let ((buffer (generate-new-buffer "*new*")))
       (set-window-buffer nil buffer)
@@ -54,17 +54,17 @@ generate `completing-read' candidates."
 If the the vertico and lsp modules are active, list lsp diagnostics for the
 current project. Otherwise list them for the current buffer"
   (interactive)
-  (cond ((and (featurep! :completion vertico)
-              (featurep! :tools lsp)
+  (cond ((and (modulep! :completion vertico)
+              (modulep! :tools lsp)
               (bound-and-true-p lsp-mode))
          (consult-lsp-diagnostics arg))
-        ((and (featurep! :checkers syntax)
+        ((and (modulep! :checkers syntax)
               (bound-and-true-p flycheck-mode))
-         (if (featurep! :completion vertico)
+         (if (modulep! :completion vertico)
              (consult-flycheck)
            (flycheck-list-errors)))
         ((bound-and-true-p flymake-mode)
-         (if (featurep! :completion vertico)
+         (if (modulep! :completion vertico)
              (consult-flymake)
            (flymake-show-diagnostics-buffer)))
         (t