common: Replace common_sizes into user-literals

Removes common_sizes.h in favor of having `_KiB`, `_MiB`, `_GiB`, etc
user-literals within literals.h.

To keep the global namespace clean, users will have to use:

```
using namespace Common::Literals;
```

to access these literals.

src/common/literals.h

@@ -0,0 +1,31 @@
+// Copyright 2021 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "common/common_types.h"
+
+namespace Common::Literals {
+
+constexpr u64 operator""_KiB(unsigned long long int x) {
+    return 1024ULL * x;
+}
+
+constexpr u64 operator""_MiB(unsigned long long int x) {
+    return 1024_KiB * x;
+}
+
+constexpr u64 operator""_GiB(unsigned long long int x) {
+    return 1024_MiB * x;
+}
+
+constexpr u64 operator""_TiB(unsigned long long int x) {
+    return 1024_GiB * x;
+}
+
+constexpr u64 operator""_PiB(unsigned long long int x) {
+    return 1024_TiB * x;
+}
+
+} // namespace Common::Literals