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/patch_manager.cpp

@@ -41,6 +41,8 @@ std::string FormatPatchTypeName(PatchType type) {
 
 PatchManager::PatchManager(u64 title_id) : title_id(title_id) {}
 
+PatchManager::~PatchManager() = default;
+
 VirtualDir PatchManager::PatchExeFS(VirtualDir exefs) const {
     LOG_INFO(Loader, "Patching ExeFS for title_id={:016X}", title_id);