refactor!: restructure Doom core

BREAKING CHANGE: This restructures the project in preparation for Doom
to be split into two repos. Users that have reconfigured Doom's CLI
stand a good chance of seeing breakage, especially if they've referred
to any core-* feature, e.g.

  (after! core-cli-ci ...)

To fix it, simply s/core-/doom-/, i.e.

  (after! doom-cli-ci ...)

What this commit specifically changes is:
- Renames all core features from core-* to doom-*
- Moves core/core-* -> lisp/doom-*
- Moves core/autoloads/* -> lisp/lib/*
- Moves core/templates -> templates/

Ref: #4273

ci.el

@@ -2,7 +2,7 @@
 ;;; Commentary:
 ;;; Code:
 
-(after! core-cli-ci
+(after! doom-cli-ci
   ;;; Commit linter types
   (add-to-list 'doom-ci-commit-types 'module)
   (add-to-list 'doom-ci-commit-scopeless-types 'module)
@@ -16,7 +16,7 @@
   ;; DEPRECATED Will be removed once modules live in their own repo
   (add-to-list 'doom-ci-commit-scopes '(release "modules")))
 
-(after! core-cli-make
+(after! doom-cli-make
   ;;; Codeowners
   ;; (dolist (path (cdr (doom-module-load-path (list doom-modules-dir))))
   ;;   (save-match-data