LibPartition: Migrate from DeprecatedFile to File

The implemented cloning mechanism should be sound:
- If a PartitionTable is passed a File with
  ShouldCloseFileDescriptor::Yes, then it will keep it alive until the
  PartitionTable is destroyed.
- If a PartitionTable is passed a File with
  ShouldCloseFileDescriptor::No, then the caller has to ensure that the
  file descriptor remains alive.
If the caller is EBRPartitionTable, the same consideration holds.
If the caller is PartitionEditor::PartitionModel, this is satisfied by
keeping an OwnPtr<Core::File> around which is the originally opened
file.

Therefore, we never leak any fds, and never access a Core::File or fd
after destroying it.

Userland/Libraries/LibPartition/CMakeLists.txt

@@ -3,6 +3,7 @@ set(SOURCES
     EBRPartitionTable.cpp
     GUIDPartitionTable.cpp
     MBRPartitionTable.cpp
+    PartitionableDevice.cpp
     PartitionTable.cpp
 )