[cmake] refactor: CPM over vcpkg (#250)

Completely replaces vcpkg with CPM for all "system" dependencies. Primarily needed for Android and Windows. Also uses my OpenSSL CI for those two platforms.

In theory, improves configure and build time by a LOT and makes things much easier to manage

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/250
Reviewed-by: Lizzie <lizzie@eden-emu.dev>

CMakeModules/DownloadExternals.cmake

@@ -35,6 +35,7 @@ function(download_bundled_external remote_path lib_name cpm_key prefix_var versi
         URL ${full_url}
         DOWNLOAD_ONLY YES
         KEY ${CACHE_KEY}
+        BUNDLED_PACKAGE ON
         # TODO(crueter): hash
     )