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/partition_filesystem.cpp

@@ -72,6 +72,8 @@ PartitionFilesystem::PartitionFilesystem(std::shared_ptr<VfsFile> file) {
     status = Loader::ResultStatus::Success;
 }
 
+PartitionFilesystem::~PartitionFilesystem() = default;
+
 Loader::ResultStatus PartitionFilesystem::GetStatus() const {
     return status;
 }