feature/workspaces: major refactor & various fixes

+ Rewrite projectile integration.
+ Fix per-frame workspaces not cleaning up after itself when an
  frame-associated workspace (or its frame) is destroyed.
+ Alias +workspace-p to perspective-p instead of persp-p (which isn't as
  accurate, because it counts nil as a valid perspective).
+ Extract orphaned-buffer list functionality in +workspace-buffer-list
  into seperate function: +workspace-orphaned-buffer-list.
+ Allow toggle-debug-on-error to catch workspace errors.
+ Remove +workspace/kill-session-and-quit (never used)
+ Ensure persp-mode is loaded as late as possible.

modules/private/default/+bindings.el

@@ -29,7 +29,7 @@
       "M-t"       #'+workspace/new
       "M-T"       #'+workspace/display
       "M-w"       #'delete-window
-      "M-W"       #'+workspace/close-workspace-or-frame
+      "M-W"       #'delete-frame
       "M-n"       #'evil-buffer-new
       "M-N"       #'make-frame
       "M-1"       (λ! (+workspace/switch-to 0))