[desktop] Data Manager, data import/export (#2700)

This adds a "Data Manager" dialog to the Tools menu. The Data Manager allows for the following operations:
- Open w/ system file manager
- Clear
- Export
- Import

On any of the following directories:
- Save (w/ profile selector)
- UserNAND
- SysNAND
- Mods
- Shaders

TODO for the future:
- "Cleanup" for each directory
- TitleID -> Game name--let users clean data for a specific game if applicable

Signed-off-by: crueter <crueter@eden-emu.dev>
Reviewed-on: eden-emu/eden#2700
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Lizzie <lizzie@eden-emu.dev>

src/frontend_common/data_manager.cpp

@@ -0,0 +1,77 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "data_manager.h"
+#include "common/assert.h"
+#include "common/fs/path_util.h"
+#include <filesystem>
+#include <fmt/format.h>
+
+namespace FrontendCommon::DataManager {
+
+namespace fs = std::filesystem;
+
+const std::string GetDataDir(DataDir dir, const std::string &user_id)
+{
+    const fs::path nand_dir = Common::FS::GetEdenPath(Common::FS::EdenPath::NANDDir);
+
+    switch (dir) {
+    case DataDir::Saves:
+        return (nand_dir / "user" / "save" / "0000000000000000" / user_id).string();
+    case DataDir::UserNand:
+        return (nand_dir / "user" / "Contents" / "registered").string();
+    case DataDir::SysNand:
+        // NB: do NOT delete save
+        // that contains profile data and other stuff
+        return (nand_dir / "system" / "Contents" / "registered").string();
+    case DataDir::Mods:
+        return Common::FS::GetEdenPathString(Common::FS::EdenPath::LoadDir);
+    case DataDir::Shaders:
+        return Common::FS::GetEdenPathString(Common::FS::EdenPath::ShaderDir);
+    default:
+        UNIMPLEMENTED();
+    }
+
+    return "";
+}
+
+u64 ClearDir(DataDir dir, const std::string &user_id)
+{
+    fs::path data_dir = GetDataDir(dir, user_id);
+    u64 result = fs::remove_all(data_dir);
+
+    // mkpath at the end just so it actually exists
+    fs::create_directories(data_dir);
+    return result;
+}
+
+const std::string ReadableBytesSize(u64 size)
+{
+    static constexpr std::array units{"B", "KiB", "MiB", "GiB", "TiB", "PiB"};
+    if (size == 0) {
+        return "0 B";
+    }
+
+    const int digit_groups = (std::min) (static_cast<int>(std::log10(size) / std::log10(1024)),
+                                         static_cast<int>(units.size()));
+    return fmt::format("{:.1f} {}", size / std::pow(1024, digit_groups), units[digit_groups]);
+}
+
+u64 DataDirSize(DataDir dir)
+{
+    fs::path data_dir = GetDataDir(dir);
+    u64 size = 0;
+
+    if (!fs::exists(data_dir))
+        return 0;
+
+    for (const auto& entry : fs::recursive_directory_iterator(data_dir)) {
+        if (!entry.is_directory()) {
+            size += entry.file_size();
+        }
+    }
+
+    return size;
+}
+
+}