file-sys: Default heavy-weight class destructors in the cpp file

Several classes have a lot of non-trivial members within them, or don't
but likely should have the destructor defaulted in the cpp file for
future-proofing/being more friendly to forward declarations.

Leaving the destructor unspecified allows the compiler to inline the
destruction code all over the place, which is generally undesirable from
a code bloat perspective.

src/core/file_sys/xts_archive.cpp

@@ -72,6 +72,8 @@ NAX::NAX(VirtualFile file_, std::array<u8, 0x10> nca_id)
                                Common::HexArrayToString(nca_id, false)));
 }
 
+NAX::~NAX() = default;
+
 Loader::ResultStatus NAX::Parse(std::string_view path) {
     if (file->ReadObject(header.get()) != sizeof(NAXHeader))
         return Loader::ResultStatus::ErrorBadNAXHeader;