[cmake] refactor: cpmfile, deps prefetch, force system and more (#322)

CPM Dependencies are now managed in a singular json file, where each can be properly prefetched at-will via `tools/cpm-fetch.sh <packages...>`, or all at once via `tools/cpm-fetch-all.sh`.

Adds docs for CPMUtil as well.

Also adds `<package>_FORCE_{BUNDLED,SYSTEM}` overrides

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/322
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/yuzu/externals/CMakeLists.txt

@@ -1,7 +1,8 @@
 # SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
 # SPDX-License-Identifier: GPL-3.0-or-later
 
-# cpm
+# Explicitly include CPMUtil here since we have a separate cpmfile for Qt externals
+set(CPMUTIL_JSON_FILE ${CMAKE_CURRENT_SOURCE_DIR}/cpmfile.json)
 include(CPMUtil)
 
 # Disable tests/tools in all externals supporting the standard option name
@@ -14,12 +15,4 @@ set(BUILD_SHARED_LIBS OFF)
 set_directory_properties(PROPERTIES EXCLUDE_FROM_ALL ON)
 
 # QuaZip
-AddPackage(
-    NAME QuaZip-Qt6
-    VERSION 1.3
-    REPO "crueter/quazip-qt6"
-    SHA f838774d63
-    HASH 9f629a438699801244a106c8df6d5f8f8d19e80df54f530a89403a10c8c4e37a6e95606bbdd307f23636961e8ce34eb37a2186d589a1f227ac9c8e2c678e326e
-    OPTIONS
-        "QUAZIP_INSTALL OFF"
-)
+AddJsonPackage(quazip)