feat: add frame specific spaces

[AlAl45643]

Description

Add frame specific spaces to allow each frame to have its own space tree instead of mirroring spaces for all frames which causes confusing behavior. This is useful for multi-monitor setups where a frame is created for each monitor.

• Make space-tree frame specific by replacing space-tree variables with space-tree--get and space-tree--set functions that use frame-parameter and set-frame-parameter respectively. Replace any calls or setqs to these space-tree variables in space-tree.el with the space-tree--get and space-tree--set functions. Also, fix any setf macros that break after replacing these variables.
• Create #'space-tree-init-frames which hooks #'space-tree-init to 'after-make-frame-functions unless it is already in 'after-make-frame-functions. Change the signature and function calls of any function called by #'space-tree--create-space-at that call or eventually call our #'space-tree-get functions so that we can can pass our frame parameter from 'after-make-functions.
• Fix tests by replacing space-tree variable calls and setqs with space-tree--get and space-tree--set functions.
• Add (space-tree-init-frames) to ## Installation in README

Testing

I didn't fix any linting issues that I didn't introduce to the code.

• eask test ert test/space-tree-test.el (all tests passed) (tests were modified with changes)

• eask lint package (no issues found)

• eask lint checkdoc
  space-tree.el with checkdoc (0.6.2)
  space-tree.el:221: Probably "runs" should be imperative "run"
  space-tree.el:338: Probably "starts" should be imperative "start"

• eask lint elisp-lint
  space-tree.el with elisp-lint (20220419.252)
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:16:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:17:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:18:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:19:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:20:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:23:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:26:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:27:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:28:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:29:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:30:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:31:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:82:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:101:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:221:0 (checkdoc) Probably "runs" should be imperative "run"
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:221:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:252:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:338:0 (checkdoc) Probably "starts" should be imperative "start"
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:472:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:496:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:509:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:553:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:719:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:727:0 (fill-column) line length 70 exceeded
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:748:0 (indent) ! "Switch to top-level space %d." 9
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:749:0 (indent) ! (list n))
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:752:0 (indent) ! "Switch to second-level space %d under the current top-level." 5
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:753:0 (indent) ! (list (nth 0 (space-tree--get-current-address)) n))
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:756:0 (indent) ! "Switch to third-level space %d under the current path." 5
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:757:0 (indent) ! (list (nth 0 (space-tree--get-current-address))
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:758:0 (indent) ! (nth 1 (space-tree--get-current-address)) n))
  /home/work/.emacs.d/elpaca/sources/space-tree/space-tree.el:758:0 (indent-character) spaces instead of tabs

• eask lint relint (no issues found)

• CI matrix (Ubuntu + Windows × Emacs 28.2, 29.4, 30.2, snapshot)