feat(corfu): impl smart confirm in minibuffer

An issue when using corfu in the minibuffer was the need for pressing
RET twice, since the first only inserts the completion. This commit
aliviates that by providing C-RET to ignore completion and conclude the
minibuffer immediatelly and S-RET to insert completion then conclude.

modules/completion/corfu/README.org

@@ -89,6 +89,8 @@ is visible, the following relevant keys are available:
 | [[kbd:][M-m]]      | Export to minibuffer (if [[doom-module::completion vertico]])        |
 | [[kbd:][M-j]]      | (evil) Export to minibuffer (if [[doom-module::completion vertico]]) |
 | [[kbd:][RET]]      | Insert candidate                                                 |
+| [[kbd:][C-RET]]    | (in minibuffer) Finish minibuffer without inserting candidate    |
+| [[kbd:][S-RET]]    | (in minibuffer) Finish minibuffer after inserting candidate      |
 | [[kbd:][SPC]]      | Quit autocompletion after a wildcard or pass-through             |
 | [[kbd:][C-SPC]]    | Complete (unless [[doom-module::completion corfu +tng]])             |
 | [[kbd:][C-SPC]]    | (when completing) Insert separator DWIM (see below)              |

modules/completion/corfu/autoload.el

@@ -1,5 +1,13 @@
 ;;; completion/corfu/autoload.el -*- lexical-binding: t; -*-
 
+;;;###autoload
+(defun +corfu-complete-and-exit-minibuffer ()
+  (interactive)
+  (if (>= corfu--index 0)
+      (corfu-complete)
+    (corfu-insert))
+  (exit-minibuffer))
+
 ;;;###autoload
 (defun +corfu-move-to-minibuffer ()
   ;; Taken from corfu's README.

modules/config/default/config.el

@@ -475,8 +475,12 @@ Continues comments if executed from a commented line. Consults
          "C-S-p" #'corfu-popupinfo-scroll-down
          "C-S-n" #'corfu-popupinfo-scroll-up
          "C-S-u" (cmd! (funcall-interactively #'corfu-popupinfo-scroll-down corfu-popupinfo-min-height))
-         "C-S-d" (cmd! (funcall-interactively #'corfu-popupinfo-scroll-up corfu-popupinfo-min-height))))
+         "C-S-d" (cmd! (funcall-interactively #'corfu-popupinfo-scroll-up corfu-popupinfo-min-height)))
-
+        (:map corfu-map
+         :gi "C-<return>" '(menu-item "Conclude the minibuffer" exit-minibuffer
+                            :enable (active-minibuffer-window))
+         :gi "S-<return>" '(menu-item "Insert completion and conclude" +corfu-complete-and-exit-minibuffer
+                            :enable (active-minibuffer-window))))
   (when-let ((cmds-del (and (modulep! :completion corfu +tng)
                             (cmds! (and (> corfu--index -1)
                                         (eq corfu-preview-current 'insert))