source-control: Change SPC gfd to magit-file-dispatch

SPC g f d  key should be more "contextual", allowing user to perform operations
associated with the current file

CHANGELOG.develop

@@ -345,6 +345,7 @@ In org-agenda-mode
 - Key bindings:
   - Changed ~SPC g h o~ to ~SPC g o~ for =browse-at-remote= (thanks to Codruț
     Constantin Gușoi)
+  - Changed ~SPC g f d~ to bind to ~magit-file-dispatch~ (thanks to Ag Ibragimov)
 ***** YAML
 - Added LSP support (thanks to Seong Yong-ju)
 ***** ycmd

layers/+source-control/git/packages.el

@@ -161,7 +161,7 @@
         "gc"  'magit-clone
         "gfF" 'magit-find-file
         "gfl" 'magit-log-buffer-file
-        "gfd" 'magit-diff
+        "gfd" 'magit-file-dispatch
         "gi"  'magit-init
         "gL"  'magit-list-repositories
         "gm"  'magit-dispatch