[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: https://git.eden-emu.dev/eden-emu/eden/pulls/2700
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Lizzie <lizzie@eden-emu.dev>

src/frontend_common/CMakeLists.txt

@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 # SPDX-FileCopyrightText: 2023 yuzu Emulator Project
 # SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -7,6 +10,7 @@ add_library(frontend_common STATIC
     content_manager.h
     firmware_manager.h
     firmware_manager.cpp
+    data_manager.h data_manager.cpp
 )
 
 create_target_directory_groups(frontend_common)