[core/file_sys] implement IApplicationFunctions::GetPseudoDeviceId; common PatchManager::GetNACP for base|updates (#4159)

a bit of refactoring so there's less code duplication...
probably a good idea to make it a lambda anyways
maybe this is why QLauncher didn't have proper DLCs and updates?

either way "GetPseudoDeviceId" is now implemented (still stubbed) with a proper hash instead of just 0

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

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4159
Reviewed-by: Maufeat <sahyno1996@gmail.com>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>

src/core/file_sys/patch_manager.h

@@ -105,6 +105,9 @@ public:
     // Version of GetControlMetadata that takes an arbitrary NCA
     [[nodiscard]] Metadata ParseControlNCA(const NCA& nca) const;
 
+    /// @brief Gets NACP metadata (accounting for any patches or updates)
+    [[nodiscard]] static PatchManager::Metadata GetMetadataFromBaseOrUpdate(Core::System& system, u64 application_id) noexcept;
+
 private:
     [[nodiscard]] std::vector<VirtualFile> CollectPatches(const std::vector<VirtualDir>& patch_dirs,
                                                           const std::string& build_id) const;