Switch between counsel-file-jump/counsel-find-file

* counsel.el (counsel-file-jump-from-find): Specify
default-directory when switching to counsel-file-jump.
(counsel-find-file): Accept new optional argument specifying
default-directory.
(counsel-find-file-from-jump): New command.
(counsel-file-jump-map): New keymap.
(counsel-file-jump): Use it.

Closes #2756.

counsel.el

@@ -1816,7 +1816,7 @@ currently checked out."
   "Switch to `counsel-file-jump' from `counsel-find-file'."
   (interactive)
   (ivy-quit-and-run
-    (counsel-file-jump ivy-text)))
+    (counsel-file-jump ivy-text (ivy-state-directory ivy-last))))
 
 (when (executable-find "git")
   (add-to-list 'ivy-ffap-url-functions 'counsel-github-url-p)
@@ -2026,14 +2026,14 @@ The preselect behavior can be customized via user options
               :caller caller)))
 
 ;;;###autoload
-(defun counsel-find-file (&optional initial-input)
+(defun counsel-find-file (&optional initial-input initial-directory)
   "Forward to `find-file'.
 When INITIAL-INPUT is non-nil, use it in the minibuffer during completion."
   (interactive)
-  (counsel--find-file-1
-   "Find file: " initial-input
-   #'counsel-find-file-action
-   'counsel-find-file))
+  (let ((default-directory (or initial-directory default-directory)))
+    (counsel--find-file-1 "Find file: " initial-input
+                          #'counsel-find-file-action
+                          'counsel-find-file)))
 
 (ivy-configure 'counsel-find-file
   :parent 'read-file-name-internal
@@ -2841,6 +2841,18 @@ FZF-PROMPT, if non-nil, is passed as `ivy-read' prompt argument."
   :type '(repeat string))
 
 ;;** `counsel-file-jump'
+(defvar counsel-file-jump-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map (kbd "`") #'counsel-find-file-from-jump)
+    map)
+  "Key bindings to be used when in a file-jump minibuffer.")
+
+(defun counsel-find-file-from-jump ()
+  "Switch to `counsel-find-file' from `counsel-file-jump'."
+  (interactive)
+  (ivy-quit-and-run
+    (counsel-find-file ivy-text (ivy-state-directory ivy-last))))
+
 ;;;###autoload
 (defun counsel-file-jump (&optional initial-input initial-directory)
   "Jump to a file below the current directory.
@@ -2861,6 +2873,7 @@ INITIAL-DIRECTORY, if non-nil, is used as the root directory for search."
               :preselect (counsel--preselect-file)
               :require-match 'confirm-after-completion
               :history 'file-name-history
+              :keymap counsel-file-jump-map
               :caller 'counsel-file-jump)))
 
 (ivy-set-actions