Make session persistence module agnostic

They've been removed from feature/workspaces and moved into
core/autoload/sessions, which falls back to desktop.el if persp-mode
isn't present. This also offers a substantial speed up to
restart+restoring and restoring sessions in general.

Also fixes #1210, where the newly spawned frame after doom/restart
wasn't focused.

Introduces the following commands:

- doom/restart
- doom/restart-and-restore
- doom/quickload-session
- doom/quicksave-session
- doom/load-session
- doom/save-session
- +workspace/restore-last-session (alias for doom/quickload-session)

And removes

- +workspace/load-session
- +workspace/save-session
- +workspace/load-last-session (renamed to +workspace/restore-last-session)
- +workspace/restart-emacs-then-restore (replaced by doom/restart-and-restore)
- :ss (ex command)
- :sl (ex command)

modules/config/default/+emacs-bindings.el

@@ -91,9 +91,9 @@
      :desc "Quit Emacs"                   "q" #'kill-emacs
      :desc "Save and quit Emacs"          "Q" #'save-buffers-kill-terminal
      (:when (featurep! :feature workspaces)
-       :desc "Quit Emacs & forget session"  "X" #'+workspace/kill-session-and-quit
-       :desc "Restart & restore Emacs"      "r" #'+workspace/restart-emacs-then-restore)
-     :desc "Restart Emacs"                "R" #'restart-emacs)
+       :desc "Quit Emacs & forget session"  "X" #'+workspace/kill-session-and-quit)
+     :desc "Restart & restore Emacs"      "r" #'doom/restart-and-restore
+     :desc "Restart Emacs"                "R" #'doom/restart)
    ;; Snippets
    "&" nil ; yasnippet creates this prefix, we use a different one
    (:prefix ("s" . "snippets")
@@ -123,15 +123,15 @@
      :desc "Previous hunk"         "[" #'git-gutter:previous-hunk)
    ;; Worspace and window management bindings
    (:prefix ("w". "workspaces")
-     :desc "Autosave session"             "a" #'+workspace/save-session
+     :desc "Autosave session"             "a" #'doom/quicksave-session
      :desc "Display workspaces"           "d" #'+workspace/display
      :desc "Rename workspace"             "r" #'+workspace/rename
      :desc "Create workspace"             "c" #'+workspace/new
      :desc "Delete workspace"             "k" #'+workspace/delete
-     :desc "Save session"                 "s" (λ! (let ((current-prefix-arg '(4))) (call-interactively #'+workspace/save-session)))
+     :desc "Save session"                 "s" #'doom/save-session
      :desc "Save workspace"               "S" #'+workspace/save
-     :desc "Load session"                 "l" #'+workspace/load-session
-     :desc "Load last autosaved session"  "L" #'+workspace/load-last-session
+     :desc "Load session"                 "l" #'doom/load-session
+     :desc "Load last autosaved session"  "L" #'doom/quickload-session
      :desc "Kill other buffers"           "o" #'doom/kill-other-buffers
      :desc "Undo window config"           "u" #'winner-undo
      :desc "Redo window config"           "U" #'winner-redo

modules/config/default/+evil-bindings.el

@@ -544,14 +544,12 @@
           :desc "Display tab bar"           "TAB" #'+workspace/display
           :desc "New workspace"             "n"   #'+workspace/new
           :desc "Load workspace from file"  "l"   #'+workspace/load
-          :desc "Load a past session"       "L"   #'+workspace/load-session
           :desc "Save workspace to file"    "s"   #'+workspace/save
-          :desc "Autosave current session"  "S"   #'+workspace/save-session
           :desc "Switch workspace"          "."   #'+workspace/switch-to
           :desc "Delete session"            "x"   #'+workspace/kill-session
           :desc "Delete this workspace"     "d"   #'+workspace/delete
           :desc "Rename workspace"          "r"   #'+workspace/rename
-          :desc "Restore last session"      "R"   #'+workspace/load-last-session
+          :desc "Restore last session"      "R"   #'+workspace/restore-last-session
           :desc "Next workspace"            "]"   #'+workspace/switch-right
           :desc "Previous workspace"        "["   #'+workspace/switch-left
           :desc "Switch to 1st workspace"   "1"   (λ! (+workspace/switch-to 0))
@@ -757,12 +755,15 @@
         :desc "List project tasks"           "t" #'+default/project-tasks
         :desc "Invalidate cache"             "x" #'projectile-invalidate-cache)
 
-      (:prefix ("q" . "quit/restart")
+      (:prefix ("q" . "session")
         :desc "Quit Emacs"                   "q" #'evil-quit-all
         :desc "Save and quit Emacs"          "Q" #'evil-save-and-quit
-        :desc "Quit Emacs & forget session"  "X" #'+workspace/kill-session-and-quit
-        :desc "Restart & restore Emacs"      "r" #'+workspace/restart-emacs-then-restore
-        :desc "Restart Emacs"                "R" #'restart-emacs)
+        :desc "Quick save current session"   "s" #'doom/quicksave-session
+        :desc "Restore last session"         "l" #'doom/quickload-session
+        :desc "Save session to file"         "S" #'doom/save-session
+        :desc "Restore session from file"    "L" #'doom/load-session
+        :desc "Restart & restore Emacs"      "r" #'doom/restart-and-restore
+        :desc "Restart Emacs"                "R" #'doom/restart)
 
       (:when (featurep! :tools upload)
         (:prefix ("r" . "remote")