refactor(lib): don't use smartparens' API

Toward our eventual goal of moving smartparens out of core, I've adapted
this from code provided by hpfr on Discord, which was adapted from
smartparen's syntax-ppss caching logic. `:config default` will need need
some attention before we can fully move smartparens to its own `:editor
smartparens` module.

Co-authored-by: hpfr <hpfr@users.noreply.github.com>

lisp/lib/help.el

@@ -355,9 +355,8 @@ without needing to check if they are available."
 
 (defun doom--help-current-module-str ()
   (cond ((save-excursion
-           (require 'smartparens)
            (ignore-errors
-             (sp-beginning-of-sexp)
+             (thing-at-point--beginning-of-sexp)
              (unless (eq (char-after) ?\()
                (backward-char))
              (let ((sexp (sexp-at-point)))