[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/cpmfile.json

@@ -0,0 +1,12 @@
+{
+    "quazip": {
+        "package": "QuaZip-Qt6",
+        "repo": "crueter/quazip-qt6",
+        "sha": "f838774d63",
+        "hash": "9f629a438699801244a106c8df6d5f8f8d19e80df54f530a89403a10c8c4e37a6e95606bbdd307f23636961e8ce34eb37a2186d589a1f227ac9c8e2c678e326e",
+        "version": "1.3",
+        "options": [
+            "QUAZIP_INSTALL OFF"
+        ]
+    }
+}