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/feature/workspaces/test/autoload-workspaces.el

@@ -10,6 +10,7 @@
                   collect `(,bsym (get-buffer-create ,(symbol-name bsym))))))
     `(let ((persp-auto-resume-time -1)
            (persp-auto-save-opt 0))
+       (require 'persp-mode)
        (let (noninteractive)
          (persp-mode +1))
        (+workspace-switch +workspaces-main t)