[cmake] refactor: Use CPM over submodules (#143)

Transfers the majority of submodules and large externals to CPM, using source archives rather than full Git clones. Not only does this save massive amounts of clone and configure time, but dependencies are grabbed on-demand rather than being required by default. Additionally, CPM will (generally) automatically search for system dependencies, though certain dependencies have options to control this.

Testing shows gains ranging from 5x to 10x in terms of overall clone/configure time.

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/143
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/dynarmic/tests/rand_int.h

@@ -0,0 +1,27 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2020 MerryMage
+ * SPDX-License-Identifier: 0BSD
+ */
+
+#pragma once
+
+#include <random>
+#include <type_traits>
+
+namespace detail {
+inline std::mt19937 g_rand_int_generator = [] {
+    std::random_device rd;
+    std::mt19937 mt{rd()};
+    return mt;
+}();
+}  // namespace detail
+
+template<typename T>
+T RandInt(T min, T max) {
+    static_assert(std::is_integral_v<T>, "T must be an integral type.");
+    static_assert(!std::is_same_v<T, signed char> && !std::is_same_v<T, unsigned char>,
+                  "Using char with uniform_int_distribution is undefined behavior.");
+
+    std::uniform_int_distribution<T> rand(min, max);
+    return rand(detail::g_rand_int_generator);
+}