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

test/test-autoload-format.el

@@ -0,0 +1,44 @@
+;; -*- no-byte-compile: t; -*-
+;;; core/test/test-autoload-message.el
+
+(describe "core/autoload/format"
+  (describe "format!"
+    :var (doom-output-backend)
+    (before-all
+      (setq doom-output-backend 'ansi))
+
+    (it "should be a drop-in replacement for `format'"
+      (expect (format! "Hello %s" "World")
+              :to-equal "Hello World"))
+
+    (it "supports ansi coloring in noninteractive sessions"
+      (expect (format! (red "Hello %s") "World")
+              :to-equal "Hello World"))
+
+    (it "supports text properties in interactive sessions"
+      (let ((doom-output-backend 'text-properties))
+        (expect (get-text-property 0 'face (format! (red "Hello %s") "World"))
+                :to-equal (list :foreground (face-foreground 'term-color-red)))))
+
+    (it "supports nested color specs"
+      (expect (format! (bold (red "Hello %s")) "World")
+              :to-equal (format "\e[%dm%s\e[0m" 1
+                                (format "\e[%dm%s\e[0m" 31 "Hello World")))
+      (expect (format! (on-red (bold "Hello %s")) "World")
+              :to-equal (format "\e[%dm%s\e[0m" 41
+                                (format "\e[%dm%s\e[0m" 1 "Hello World")))
+      (expect (format! (dark (white "Hello %s")) "World")
+              :to-equal (format "\e[%dm%s\e[0m" 2
+                                (format "\e[%dm%s\e[0m" 37 "Hello World"))))
+
+    (it "supports dynamic color apply syntax"
+      (expect (format! (color 'red "Hello %s") "World")
+              :to-equal (format! (red "Hello %s") "World"))
+      (expect (format! (color (if nil 'red 'blue) "Hello %s") "World")
+              :to-equal (format! (blue "Hello %s") "World"))))
+
+  (xdescribe "insert!")
+  (xdescribe "print!")
+  (xdescribe "print-group!")
+  (xdescribe "error!")
+  (xdescribe "user-error!"))