[vfs] remove usage of 'dynamic_cast', use ankerl::map for files (#3594)

Do I need to writeout everything wrong with `dynamic_cast`?

Also the usual std::map -> `ankerl::unordered_dense::map` conversion, seems to work just fine - but of course test that updates/DLCs/mods/cheats/etc are still being applied :)

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3594
Reviewed-by: DraVee <dravee@eden-emu.dev>
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/core/file_sys/nca_metadata.h

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -37,6 +40,7 @@ enum class ContentRecordType : u8 {
     HtmlDocument = 4,
     LegalInformation = 5,
     DeltaFragment = 6,
+    Count,
 };
 
 struct ContentRecord {