feat(workspaces): replace desktop.el with easysession

It seems easysession is a more modern take on session management, and
most importantly, it is much faster than desktop.el. So far this seems
to work fine, so I'll give it a proper try.

modules/workspaces/siren-easysession.el

@@ -0,0 +1,41 @@
+;;; siren-easysession.el --- jimeh's Emacs Siren: easysession configuration.
+
+;;; Commentary:
+
+;; Basic configuration for easysession.
+
+;;; Code:
+
+(use-package easysession
+  :ensure t
+  :hook
+  (easysession-after-load . siren-easysession-after-load)
+  ((easysession-after-load easysession-new-session-hook) . siren-easysession-setup)
+
+  :general
+  ("C-z C-z c" 'easysession-save-as)
+  ("C-z C-z C-c" 'easysession-save-as)
+  ("C-z C-z k" 'easysession-delete)
+  ("C-z C-z C-k" 'easysession-delete)
+  ("C-z C-z r" 'easysession-rename)
+  ("C-z C-z C-r" 'easysession-rename)
+  ("C-z C-z l" 'easysession-load)
+  ("C-z C-z C-l" 'easysession-load)
+  ("C-z C-z s" 'easysession-switch-to)
+  ("C-z C-z C-s" 'easysession-switch-to)
+
+  :custom
+  (easysession-save-interval 10)
+  (easysession-mode-line-misc-info nil)
+
+  :preface
+  (defun siren-easysession-setup ()
+    "Enable easysession-save-mode."
+    (easysession-save-mode +1))
+
+  (defun siren-easysession-after-load ()
+    ;; Ensure tab-bar-mode bar is correctly enabled after a session load.
+    (tab-bar-mode +1)))
+
+(provide 'siren-easysession)
+;;; siren-easysession.el ends here