refactor(cli): remove :stub, :obsolete, :deprecated, :since

I've removed these CLI properties because they were either
unused (:deprecated and :since) or poorly implemented (:stub and
:obsolete). And I'd rather have fewer magical properties, and instead
delegate these roles to the defobsolete! and (new) defstub!  macros.
Also, in the future, the help API will ascertain :since dynamically, so
it won't be very useful.

In summary:
- Use defstub! instead of :stub
- Use defobsolete! instead of :obsolete or :deprecated
- This removes the doom-cli-deprecated-error type (it's not really an
  error to begin with).
- Removes :stub, :obsolete, :deprecated, and :since

core/cli/ci.el

@@ -319,7 +319,7 @@ Note: warnings are not considered failures.")
        commits))))
 
 ;;; TODO
-(defcli! (ci run-tests) (&rest targets) :stub t)
+(defstub! (ci run-tests))
 
 ;;; doom ci hook
 (defcli! (ci hook commit-msg) (file)