BAN: Implement Ext2 file unlinking

Ext2 inodes can now be unlinked from directories and after last
inode closes (destructor gets called) we check if link count is 0
and cleanup the inode from filesystem

kernel/kernel/FS/ProcFS/FileSystem.cpp

@@ -40,7 +40,7 @@ namespace Kernel
 	void ProcFileSystem::on_process_delete(Process& process)
 	{
 		auto path = BAN::String::formatted("{}", process.pid());
-		MUST(m_root_inode->delete_inode(path));
+		MUST(m_root_inode->unlink(path));
 	}
 
 }