[org] keybindings for managing org agenda files

Modeled after the builtin style, which is fairly mnemonic already.

CHANGELOG.develop

@@ -2925,6 +2925,8 @@ files (thanks to Daniel Nicolai)
 - Fixed ocamlformat not properly initialized by following do (thanks to Nicolas Raymond)
 - Allow new OPAM share commandline syntax (thanks to Cody McKenzie)
 **** Org
+- Add ~SPC m [~ for =org-agenda-file-to-front= and ~SPC m ]~ for =org-remove-file=
+  (thanks to Keith Pinson).
 - Add initial =org-transclusion= support behind =org-enable-transclusion-support=
   flag (thanks to Keith Pinson).
 - When =org-appear= is set to be triggered manually and Spacemacs' editing mode is

layers/+emacs/org/README.org

@@ -890,6 +890,8 @@ The evilified org agenda supports the following bindings:
 |----------------------+-----------------------------------|
 | ~M-SPC~ or ~s-M-SPC~ | org-agenda transient state        |
 | ~SPC m a~            | org-agenda                        |
+| ~SPC m [~            | org-agenda-file-to-front          |
+| ~SPC m ]~            | org-remove-file                   |
 | ~SPC m ,~            | org-agenda-ctrl-c-ctrl-c          |
 | ~SPC m c~            | org-agenda-capture                |
 | ~SPC m C c~          | org-agenda-clock-cancel           |

layers/+emacs/org/packages.el

@@ -256,6 +256,8 @@ Will work on both org-mode and any mode that accepts plain html."
         "fu" 'org-feed-update-all
 
         "a" 'org-agenda
+        "[" 'org-agenda-file-to-front
+        "]" 'org-remove-file
 
         "p" 'org-priority