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/lang/org/config.el

@@ -478,7 +478,7 @@ relative to `org-directory', unless it is an absolute path."
     :after #'org-capture-refile
     (+org-capture-cleanup-frame-h))
 
-  (when (featurep! :ui doom-dashboard)
+  (when (modulep! :ui doom-dashboard)
     (add-hook '+doom-dashboard-inhibit-functions #'+org-capture-frame-p)))
 
 
@@ -514,7 +514,8 @@ relative to `org-directory', unless it is an absolute path."
    :face (lambda (path)
            (if (or (file-remote-p path)
                    ;; filter out network shares on windows (slow)
-                   (and IS-WINDOWS (string-prefix-p "\\\\" path))
+                   (and (featurep :os 'windows)
+                        (string-prefix-p "\\\\" path))
                    (file-exists-p path))
                'org-link
              '(warning org-link))))
@@ -599,15 +600,15 @@ relative to `org-directory', unless it is an absolute path."
         org-html-validation-link nil
         org-latex-prefer-user-labels t)
 
-  (when (featurep! :lang markdown)
+  (when (modulep! :lang markdown)
     (add-to-list 'org-export-backends 'md))
 
   (use-package! ox-hugo
-    :when (featurep! +hugo)
+    :when (modulep! +hugo)
     :after ox)
 
   (use-package! ox-pandoc
-    :when (featurep! +pandoc)
+    :when (modulep! +pandoc)
     :when (executable-find "pandoc")
     :after ox
     :init
@@ -847,7 +848,7 @@ between the two."
         [C-return]   #'+org/insert-item-below
         [C-S-return] #'+org/insert-item-above
         [C-M-return] #'org-insert-subheading
-        (:when IS-MAC
+        (:when (featurep :os 'macos)
          [s-return]   #'+org/insert-item-below
          [s-S-return] #'+org/insert-item-above
          [s-M-return] #'org-insert-subheading)
@@ -863,13 +864,13 @@ between the two."
         "," #'org-switchb
         "." #'org-goto
         "@" #'org-cite-insert
-        (:when (featurep! :completion ivy)
+        (:when (modulep! :completion ivy)
          "." #'counsel-org-goto
          "/" #'counsel-org-goto-all)
-        (:when (featurep! :completion helm)
+        (:when (modulep! :completion helm)
          "." #'helm-org-in-buffer-headings
          "/" #'helm-org-agenda-files-headings)
-        (:when (featurep! :completion vertico)
+        (:when (modulep! :completion vertico)
          "." #'consult-org-heading
          "/" #'consult-org-agenda)
         "A" #'org-archive-subtree
@@ -900,7 +901,7 @@ between the two."
          "u" #'org-attach-url
          "s" #'org-attach-set-directory
          "S" #'org-attach-sync
-         (:when (featurep! +dragndrop)
+         (:when (modulep! +dragndrop)
           "c" #'org-download-screenshot
           "p" #'org-download-clipboard
           "P" #'org-download-yank))
@@ -926,7 +927,7 @@ between the two."
          (:prefix ("t" . "toggle")
           "f" #'org-table-toggle-formula-debugger
           "o" #'org-table-toggle-coordinate-overlays)
-         (:when (featurep! +gnuplot)
+         (:when (modulep! +gnuplot)
           "p" #'org-plot/gnuplot))
         (:prefix ("c" . "clock")
          "c" #'org-clock-cancel
@@ -951,13 +952,13 @@ between the two."
          "T" #'org-time-stamp-inactive)
         (:prefix ("g" . "goto")
          "g" #'org-goto
-         (:when (featurep! :completion ivy)
+         (:when (modulep! :completion ivy)
           "g" #'counsel-org-goto
           "G" #'counsel-org-goto-all)
-         (:when (featurep! :completion helm)
+         (:when (modulep! :completion helm)
           "g" #'helm-org-in-buffer-headings
           "G" #'helm-org-agenda-files-headings)
-         (:when (featurep! :completion vertico)
+         (:when (modulep! :completion vertico)
           "g" #'consult-org-heading
           "G" #'consult-org-agenda)
          "c" #'org-clock-goto
@@ -1107,7 +1108,7 @@ between the two."
 
 
 (use-package! org-pdftools
-  :when (featurep! :tools pdf)
+  :when (modulep! :tools pdf)
   :commands org-pdftools-export
   :init
   (after! org
@@ -1137,7 +1138,7 @@ between the two."
 
 
 (use-package! evil-org
-  :when (featurep! :editor evil +everywhere)
+  :when (modulep! :editor evil +everywhere)
   :hook (org-mode . evil-org-mode)
   :hook (org-capture-mode . evil-insert-state)
   :hook (doom-docs-org-mode . evil-org-mode)
@@ -1219,7 +1220,7 @@ between the two."
 
 
 (use-package! evil-org-agenda
-  :when (featurep! :editor evil +everywhere)
+  :when (modulep! :editor evil +everywhere)
   :hook (org-agenda-mode . evil-org-agenda-mode)
   :config
   (evil-org-agenda-set-keys)
@@ -1304,7 +1305,7 @@ between the two."
     "Advise `server-visit-files' to load `org-protocol' lazily."
     :around #'server-visit-files
     (if (not (cl-loop with protocol =
-                      (if IS-WINDOWS
+                      (if (featurep :os 'windows)
                           ;; On Windows, the file arguments for `emacsclient'
                           ;; get funnelled through `expand-file-path' by
                           ;; `server-process-filter'. This substitutes