Another which-key keymap based replacements implementation

[leifhelm]

I started working on implementing which-key keymap based replacements at the same time as @jgrey4296 (#481) as suggested in #193.
As I am no expert in programming with emacs lisp I choose to use which-key-add-keymap-based-replacements.
I did not correct the which-key tests yet.

[noctuid]

I will look at both your PRs next week, but if they both work, I will probably go with yours once tests are working since it is simpler.

[noctuid]

I think completely replacing the old mechanism should be okay since all the regexps were auto-generated and not complicated (no functionality should be lost).

The only issue is that this needs to handle :definer 'minor-mode (should check kargs to determine whether to pass t for the next argument to general--get-keymap).

If you want to fix the minor mode issue, go ahead. I can take care of the tests and documentation.

Left to be done:

• fix handling for evil-define-minor-mode-key
• rewrite all tests to inspect keymaps instead
• rewrite documentation; mention old keywords are deprecated and date which-key implemented this functionality