[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>

externals/dynarmic/tests/fuzz_util.h

@@ -1,34 +0,0 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
-// SPDX-License-Identifier: GPL-3.0-or-later
-
-/* This file is part of the dynarmic project.
- * Copyright (c) 2018 MerryMage
- * SPDX-License-Identifier: 0BSD
- */
-
-#pragma once
-
-#include <array>
-#include <iosfwd>
-
-#include "dynarmic/common/common_types.h"
-
-using Vector = std::array<u64, 2>;
-
-std::ostream& operator<<(std::ostream& o, Vector vec);
-Vector RandomVector();
-u32 RandomFpcr();
-
-struct InstructionGenerator final {
-public:
-    explicit InstructionGenerator(const char* format);
-
-    u32 Generate() const;
-    u32 Bits() const { return bits; }
-    u32 Mask() const { return mask; }
-    bool Match(u32 inst) const { return (inst & mask) == bits; }
-
-private:
-    u32 bits = 0;
-    u32 mask = 0;
-};